1.5(2x-7y)-3(4x-10y)
=10x-35y-12x+30y
=-2x-5y
=-(2x-5y)
2.-4(5a-b)+3(-3分之1a+3分之4b+1)
=-20a+4b-a+4b+1
=-21a+8b+1
=8b-21a+1