4(7-5x)-(12-20x)
2(3x-y)-(5x-2y)
6(x+2y)-3(2x+y)
5(4x+y)-2(x-y)

4 (7-5)-(12-20х)=28-20х-12+20=16
2 (3х-у)-(5х-2у)=6х-2у-5х+2у=х
6 (х+2у)-3 (2х+у)=6х+12у-6х-3у=9
5 (4х+у)-2 (х-у)=20х+5у-2х+2у=18х+10у