`c) [2(x-y)^3-7(x-y)^2-(y-x)]:(x-y)`
`=[2(x-y)^3-7(x-y)^2+(x-y)]:(x-y)`
`=[2(x-y)^3]:(x-y)-[7(x-y)^2]:(x-y)+(x-y):(x-y)`
`=2(x-y)^2-7(x-y)+1`
`=2(x^2-2xy+y^2)-7x+7y+1`
`=2x^2-4xy+2y^2-7x+7y+1`
`d) [3(x-y)^5-2(x-y)^4+3(x-y)^2]:[5(x-y)^2]`
`=[3(x-y)^5]:[5(x-y)^2]-[2(x-y)^4]:[5(x-y)^2]+[3(x-y)^2]:[5(x-y)^2]`
`=3/5(x-y)^3-2/5(x-y)^2+3/5`
`=3/5(x^3-3x^2y+3xy^2-y^3)-2/5(x^2-2xy+y^2)+3/5`
`=3/5x^3-9/5x^2y+9/5xy^2-3/5y^3-2/5x^2+4/5xy-2/5y^2+3/5`