



 
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
I hope this helps,  


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