Calculati:
a) (-2a)(-4a) -(+5a)(-2a)-(+3a)(+4a)+(-3a)(-6a)=
b)(-5x)(-3x)-(-4a)(+2a)-(-3a)(-7a)+(-5a)(+6a)=
c)3(3x+2y-6)-5(4x-3y-2)+7(3x-5y-1)
d)4(2a-3b+4c)+2(3a+2b-3c)-3(a-2b+2c)=

DAU COROANA VA ROG FRUMOS!!!!!!