Question

упростите выражение 2x-21/x-y-3 - 5x-7y/3+y-x

Answer 1

(2x-21)/(x-y-3)-(5x-7y)/(3+y-x)= (2x-21+5x-7y)/(x-y-3)= (7x-7y-21)/(x-y-3)