ADDITION AND SUBTRACTION EQUATIONS

About "Addition and subtraction equations"

Addition and subtraction equations are the equations which contain addition or subtraction. 

For example, 

x + 5  =  7

y - 3  =  4

Let us see, how to solve equations which contain addition or subtraction. 

Solving addition and subtraction equations - Examples

Example 1 :

Solve for x :  x + 7  =  8

Solution :

x + 7  =  8

Since we are trying to solve for "x", we have to get rid of 7 which is added to "x".

To get rid of 7, we have to take -7 on both sides. 

aaaaaaaaaaaaaaaaaaaaaaax + 7  =  8 aaaaaaaaaaaaaaaaaaaaaaaaa- 7aa- 7 aaaaaaaaaaaaaaaaaaaaaa------------- aaaaaaaaaaaaaaaaaaaaaaax        =  1 aaaaaaaaaaaaaaaaaaaaaa-------------

Hence, the value of "x" is 1.

Example 2 :

Solve for y :  y - 3  =  2

Solution :

y - 3  =  2

Since we are trying to solve for "y", we have to get rid of 3 which is subtracted from "y".

To get rid of 3, we have to take +3 on both sides. 

aaaaaaaaaaaaaaaaaaaaaay - 3  =  2                 aaaaaaaaaaaaaaaaaaaaaaaa + 3       + 3                                 aaaaaaaaaaaaaaaaaaaaa-----------------                               aaaaaaaaaaaaaaaaaaaaaay            =   5                                 aaaaaaaaaaaaaaaaaaaaa-----------------

Hence, the value of "y" is 5.

Example 3 :

When 7 is added to a number, we get 25. Find the number. 

Solution : 

Let "x' be the required number. 

According to the question, we have

x + 7  =  25

Here "7" is added to "x". To get rid of 7, we have to subtract 7 on both sides and solve the equation as explained below.  

(x + 7) - 7  =  (25) - 7

x  =  18

Hence, the required number is "18".

Example 4 :

John had some candies. He gave 5 candies to his friend and now he has 18 candies. How many candies did John initially have ? 

Solution : 

Let "m' be the no. of candies that John initially had. 

According to the question, we have

m - 5   =  18

Here "5" is subtracted from "m". To get rid of 5, we have to add 5 on both sides and solve the equation as explained below.  

(m - 5) + 5  =  18 + 5

m  =  23

Hence, John initially had 23 candies.

Example 5 :

The sum of two numbers 22.5. If one number is 7.5, find the other number. 

Solution : 

Let "x' be the other number. 

According to the question, we have

x + 7.5   =  22.5

Here "7.5" is added to "x". To get rid of 7.5, we have to subtract 7.5 on both sides and solve the equation as explained below.  

(x + 7.5) - 7.5  =  22.5 - 7.5

x  =  15

Hence, the other number is 15.

After having gone through the stuff given above, we hope that the students would have understood "Addition and subtraction equations". 

Apart from the stuff given above, if you want to know more about "Addition and subtraction equations", please click here

Apart from the stuff given in this section, if you need any other stuff in math, please use our google custom search here.

You can also visit the following web pages on different stuff in math. 

WORD PROBLEMS

HCF and LCM  word problems

Word problems on simple equations 

Word problems on linear equations 

Word problems on quadratic equations

Algebra word problems

Word problems on trains

Area and perimeter word problems

Word problems on direct variation and inverse variation 

Word problems on unit price

Word problems on unit rate 

Word problems on comparing rates

Converting customary units word problems 

Converting metric units word problems

Word problems on simple interest

Word problems on compound interest

Word problems on types of angles 

Complementary and supplementary angles word problems

Double facts word problems

Trigonometry word problems

Percentage word problems 

Profit and loss word problems 

Markup and markdown word problems 

Decimal word problems

Word problems on fractions

Word problems on mixed fractrions

One step equation word problems

Linear inequalities word problems

Ratio and proportion word problems

Time and work word problems

Word problems on sets and venn diagrams

Word problems on ages

Pythagorean theorem word problems

Percent of a number word problems

Word problems on constant speed

Word problems on average speed 

Word problems on sum of the angles of a triangle is 180 degree

OTHER TOPICS 

Profit and loss shortcuts

Percentage shortcuts

Times table shortcuts

Time, speed and distance shortcuts

Ratio and proportion shortcuts

Domain and range of rational functions

Domain and range of rational functions with holes

Graphing rational functions

Graphing rational functions with holes

Converting repeating decimals in to fractions

Decimal representation of rational numbers

Finding square root using long division

L.C.M method to solve time and work problems

Translating the word problems in to algebraic expressions

Remainder when 2 power 256 is divided by 17

Remainder when 17 power 23 is divided by 16

Sum of all three digit numbers divisible by 6

Sum of all three digit numbers divisible by 7

Sum of all three digit numbers divisible by 8

Sum of all three digit numbers formed using 1, 3, 4

Sum of all three four digit numbers formed with non zero digits

Sum of all three four digit numbers formed using 0, 1, 2, 3

Sum of all three four digit numbers formed using 1, 2, 5, 6