a, \(20x-5y=5\left(4x-y\right)\)
b, \(5x\left(x-1\right)-3\left(x-1\right)=\left(x-1\right)\left(5x-3\right)\)
c, \(x\left(x+y\right)-6x-6y=x\left(x+y\right)-6\left(x+y\right)=\left(x+y\right)\left(x-6\right)\)
e, \(4x^2y-8xy^2+10x^2y^2=2xy\left(2x-4y+5xy\right)\)
h, \(8x^4+12x^2y^4-16x^3y^4=4x^2\left(2x^2+3y^4-4xy^4\right)\)