It's 5(n+7)=40 because 5 + 7n = 40 and 5n + 7 = 40 is addition not multiplication, and 5⋅7+n=40 is saying 5 times seven plus a number is 40, therefore 5(n+7)=40 is the correct answer because the parenthesis in (n+7) seperates it from 5 so that you have to get the sum of (n+7) before you can multiply it by 5.
