Answer:
27
Step-by-step explanation:
Use some version of PEMDAS (I forget the others but it has the same gist)
We first do items inside parentheses
12 + 3*(5)
Multiplication/division
12+15
Addition/subtraction
27
You could also take an algebraic approach. Instead of subtracting in the parentheses, you could distribute the three
12 + 24 - 9
Then solve left to right
