1) (2x-y)(x+4y) + 2x(y-3x) = 2x^2+8xy-xy-4y^2 + 2xy-6x^2 = -4x^2+9xy-4y^2
2)5a(2x-a)-(8a-x)(2x-a) = 10ax-5a^2 -(16ax-8a^2-2x^2+ax) = 10ax-5a^2-16ax+8a^2+2x^2-ax = -7ax+3a^2+2x^2
3)ax(2x-3d) - x(ax+5a^2) = ax^2 - 3axd - ax^2 - 5a^2x
4)-a^2(3a-5) + 4a(a^2 - a) = -3a^3+5a^2 + 4a^3 - 8a^2 = a^3 - 3a^2
5)5+x^2/x^2-36 - x/x+6 = 5+x^2/(x-6)(x+6) - x/x+6 = 5 + x^2 - x(x-6) = 5 + x^2 - x^2+ 6x = 6x+5
6)2m/m-4 - 5m-2/m^2-16 = 2m/m-4 - 5m-2/(m-4)(m+4) = 2m(m+4)-5m-2 = 2m^2+8m-5m-2 = 2m^2+3m-2