1
6с/(7c-5m)-(2c-2m)/(2c-5m)=(12c²-10cm-14cm+10m²)/(7c-5m)(2c-5m)=
=(26c²-54cm+10m²)/(7c-5m)(2c-5m)
2
(3b+4z)/(b+5z)-(5z-2b)/(2z-5b)=
=(6bz-15b²+8z²-20bz-5bz-25z²+2b²+10bz)/(b+5z)(2z-5b)=
=(-13b²-9bz-17z²)/(b+5z)(2z-5b)=(13b²+9bz+17z²)/(b+5z)(5b-2z)
3
(4d-2m)/(d+4m)-(5d-6m)/(4d-4m)=
=(16d²-16dm-8dm+8m²-5d²-20dm+6dm+24m²)/(d+4m)(4d-4m)=
=(11d²-38dm+32m²)/(d+4m)(4d-4m)