Given equation is 3(-a-3)-2(3a+3)=-78
we can start by distributing numbers which are outside parenthesis
3(-a-3)-2(3a+3)=-78
-3a-9-6a-6=-78
combine like terms
-9a-15=-78
-9a=-78+15
-9a=-63
a=-63/-9
a=7
Hence final answer is a=7.
We are given this equation:
3(-a-3)-2(3a+3)=-78
We will use distributive property here :
a(b+c) =a*b +a*c
-3a-9 -6a-6=-78
combining like terms
-9a - 15 =-78
we add 15 to both sides
-9a -15 +15 = -78+15
-9a =-63
dividing both sides by -9
a=7
