Explaining step by step the simplest form of the expression 9r (r+3) - 2r (r-4)

For simplest form, the first thing you'll want to do is get rid of the parentheses:

9r (r + 3) - 2r (r - 4) = 9r^2 + 27r - 2r^2 + 8r

Now we want to combine like terms:

9r^2 + 27r - 2r^2 + 8r = 7r^2 + 35r