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".
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