Answer
$24r^2-15r$
Work Step by Step
We start with the given expression: $3(2r+4r^2-7r+4r^2)$
We apply the distributive property: $6r+12r^2-21r+12r^2$
We rearrange the terms using the commutative property of addition: $12r^2+12r^2+6r-21r$
We combine like terms using addition and subtraction: $24r^2-15r$
