Combine like terms to write the expression in standard form (−r +s) + (s − r)

First we clear brackets

 -r+s+s-r

Second we collect like terms

-r-r+s+s

then we add it

-2r +2s

if we read the question it says standard form so we out the G.C.F of the

expression

2(-r+s)

2 5/8 is the final answer! : )