Step by step
The question
Question: solve x/3 = 4.
There are four choices.
First we solve it, the normal way.
Then we pick.
1 Remove the fraction
The bottom number is 3.
A fraction means divide: x/3 is x divided by 3.
To remove divided by 3, we multiply by 3.
We multiply every part by 3, not only the fraction.
Each whole side is times 3, so 4 is times 3 too.
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.
3 divided by 3 is 1.
The bottom is gone.
We write it again, without the crossed-out parts.
3 times 4 is 12.
No more fractions!
So x = 12!
2 Check
Let's check: put 12 in place of x.
We get 4, the same as the right side.
So x = 12 is right!
3 Pick the choice
Our answer is x = 12.
That is choice D.
4 Why not the others
A is 1.
Wrong: 4 − 3: took away 3.
B is 4/3.
Wrong: 4 ÷ 3: divided instead of multiplying.
C is 7.
Wrong: 4 + 3: added 3.
Let's look back.
First: remove the fraction.
Then: check.
Then: pick the choice.
Last: why not the others.