To do this problem, you need to first get rid of all the parenthesis. Since all the operations are addition (+), remember the <span>Associative Property of Addition. This property says when you're adding, it doesn't matter where you put the parentheses because it'll all add up to the same thing.
That means </span>(3b + 2r) + (4b + r) = (3b + 4b) + (2r + r), or even, just get rid of the paratheses in general and have (3b + 2r) + (4b + r) = (3b + 2r + 4b + r).
Either way, now you can add like terms so: (3b + 2r) + (4b + r) = (3b + 4b) + (2r + r) = 7b + 3r
