Respuesta :

First, you need to distribute 4 throughout the parenthesis.

You get 45 = 4a +12 - 3

Put 12 and 3 together.

45 = 4a + 9

Subtract 9 from both sides.

36 = 4a

Divide each side by 4 and you have your answer.
45 = 4(a+3)-3
45+3 = 4(a+3)
48 = 4(a+3)
48/4 = a+3
12 = a+3
a = 9