Step by step
The question
Question: solve x + 7 = 12.
x + 7 = 12
1 Remove the + 7
We want x by itself.
The + 7 is in the way.
To remove + 7, we take away 7.
We do it on both sides.
Why both sides?
The = sign means both sides are the same amount.
If we change only one side, they are not the same any more.
x + 7 − 7 = 12 − 7
+ 7 and − 7 make zero.
Cross them out.
12 − 7 = 5.
12 − 7 = 5
So x = 5!
x = 5
2 Check
Let's check: put 5 in place of x.
Check: 5 + 7 = 12
We get 12, the same as the right side.
So x = 5 is right!
Let's look back.
First: remove the + 7.
Last: check.
Answer
x = 5