Answer:
11
Step-by-step explanation:
Given two expressions involving the same unknown number, you want to find the number.
Setup
3(x +4) . . . . three times the sum of a number and 4
6x -21 . . . . 21 less than the number times 6
These two expressions have the same value, so we can write the equation ...
3(x +4) = 6x -21
Solution
Eliminating parentheses, we have ...
3x +12 = 6x -21
33 = 3x . . . . . . . . add 21-3x
11 = x . . . . . . . . . divide by 3
The number is 11.
