Question

3rs - 5cr - 15cs + 25c2

Answer 1

$3rs-5cr-15cs+25c^2=r(3s-5c)-5c(3s-5c)\\\\=(3s-5c)(r-5c)\\\\Answer:\ \boxed{3rs-5cr-15cs+25c^2=(3s-5c)(r-5c)}$

Answer 2

Your answer would be 3rs-5cr-15cs+50c

A trick that I have learned, but does not apply to all equations, (some don’t work with this) is to multiply +25c by 2 to get =50c.