a) 3(a-2b+4)=3a-6b+12=3(a-2b+4)
b) -2(3x-7-y)=-6x+14+2y=2(-3x+y+7)
c) 5(x-2-5)=5(x-7)=5x-35=5(x-7)
c)5(x-2-5)=5x-10-25=5(x-2-5) dopisz y
d) 7(a-2b+3)=7a-14b+21=7(a-2b+3)
e) -\frac{1}{2} (2x+4y-6)=-x-2y+3
f) \frac{1}{4}(-3x^2-8x+2)=-\frac{3}{4}x^2-2x+\frac{1}{2}=-0,75x^2-2x+0,5