When - 3 is multiplied by the sum of a number and 8, the result is - 21. Find the number.

A.

3

B.

-1

C.

8

D.

-2

-3 times (x+8) = - 21

-3 (x+8) = - 21

distributive property=a (b+c) = ab+ac

-3 (x+8) = - 3x + (-3) (8) = - 3x-24

-3x-24=-21

add 3x to both sides

-24=-21+3x

add 21 to both sides

-3=3x

divide both sids by 3

-1=x

x=-1