ա) (2a²b-10b³)-(4a²b-12b³)=2a²b-10b³-4a²b+12b³=-2a²b+2b³

բ) (3xy²+7x²y)-(2xy²-6x²y)=3xy²+7x²y-2xy²+6x²y=xy²+13x²y

գ) 12ab-30bc-3cx-(15bc+9cx)=12ab-30bc-3cx-15bc-9cx=12ab-45bc-12cx

դ) (10abc-8bcx-21cxy)-(-6abc+bcx-cxy)=10abc-8bcx-21cxy+6abc-bcx+cxy=16abc-9bcx-20cxy

ե) (0,6ab-0,5bc+cx)-(2,5bc-0,5ab-cx)=0,6ab-0,5bc+cx-2,5bc+0,5ab+cx=1,1ab-3bca+2cx

զ) (1/2x²y²-2/3ab-5/6a²b-1)-(a²b-1/3x²y²+1/12ab-1/4)=1/2x²y²-2/3ab-5/6a²b-1-a²b+1/3x²y²-1/12ab+1/4=5/6x²y²-9/12ab-11/6a²b-3/4