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