Respuesta :

nariisnapping
Turn it into an equation then solve.

3 (x + 21) = 12
3x + 63 = 12
3x = -51
x = -17
Cascade
Answer: x = -17

Form your equation, where x is the number.
3(x + 21) = 12

Solve for x.
3(x + 21) = 12           Distributive Property
3x + 63 = 12            Subtract 63 from both sides
3x = -51                   Divide by 3 to both sides
x = -17                     Answer!