Question

Randy is thinking of a number. When he adds 7 to the number, multiplies the sum by 3, then subtracts 2, the result is 13. What is the original number?

A. 6
B. -2
C. 2
D. -6

Answer 1

B. -2

Explanation:

let the number be x

=7+x

=3(7+x)

=3(7+x)-2

13=3(7+x)-2

solving for x we have

13=21+3x-2

21+3x-2-13=0

collect like terms we have

21-2-13+3x=0

6+3x=0

6=-3x

x=6/-3

x=-2

The answer is B

B. -2