Hi Rob,

The parentheses act like commas in an English sentence. They group together operations that should be performed first. Thus, since 22 - 7 = 15 this expression becomes 8 + 4(15).

The operation between the 4 and the 15 is multiplication. This is a convention in mathematical expressions. Thus in your expression you have a multiplication and an addition. Again the convention is to perform multiplications before additions so you have

8 + 4 (15) = 8 + 60 = 68.

I hope this helps,
Penny