Three times the difference of a number and 7 is 30. Find the number.

Answer 1

Since the question says "three times the difference", the difference is in parentheses and happens first.

3 times (x-7) is 30 becomes 3*(x-7)=30.

Solve by dividing each side by three to get x-7=10.

Then add seven to each side to get x=17.

The number is 17.

Answer 2

3x=30

x=10

We now know that the resulting number has to be 10, so all we need to do now is add it to 7. 17-7=10, and 3*10=30.