`C=(2x+y)(2z+y)+(x-y)(y-2)`
`C=4xz+2xy+2yz+y^2+xy-2x-y^2+2y`
`C=4xz+3xy+2yz-2x+2y`
--------------------------
`D=3x(x-2y)-7/6y(y-6x)`
`D=3x^2-6xy-7/6y^2+7xy`
`D=3x^2+xy-7/6y^2`
--------------------------
`E=2x(10x^2-5x-2)-5x(4x^2-2x-1)`
`E=20x^3-10x^2-4x-(20x^3-10x^2-5x)`
`E=20x^3-10x^2-4x-20x^3+10x^2+5x`
`E=x`
--------------------------
`F=a(a+1/3)-(1/5a+8)(5a-11)`
`F=a^2+1/3a-(a^2-11/5a+40a-88)`
`F=a^2+1/3a-(a^2+189/5a-88)`
`F=a^2+1/3a-a^2-189/5a+88`
`F=-562/15a+88`