Question

$7r\left(4rs-5s^2\right)-3r\left(-6rs+15s^2\right)-4r\left(-rs-2s^3\right)​$

Answer 1

$7r\left(4rs-5s^2\right)-3r\left(-6rs+15s^2\right)-4r\left(-rs-2s^3\right)$

$=28r^2s-35rs^2-3r\left(-6rs+15s^2\right)-4r\left(-rs-2s^3\right)$

$=28r^2s-35rs^2+18r^2s-45rs^2-4r\left(-rs-2s^3\right)$

$=28r^2s-35rs^2+18r^2s-45rs^2+4r^2s+8rs^3$

$=50r^2s+8rs^3-80rs^2$

Hope it Helped !!!