Question

I'm thinking of a number and if I subtract 8 and
multiply by -3, I get 21, what is my number?

Answer 1

The number is 1

Explanation:

Let the number be x
Subtract 8 from x ==> x - 8

Multiply by -3 ==> -3(x - 8) = -3(x) -3(-8) = -3x - 24

This equals 21

So
-3x + 24 = 21

Subtract 24 from both sides:
-3x + 24 - 24 = 21 - 24

==> -3x + 0 = - 3

-3x = -3

Divide by -3

==> -3x/-3 = -3/-3

x = 1

Check

1 - 8 = -7

-3(1-8) = -3 x -7 = 21

Answer 2

15

Explanation: