a) 3(5a+3b)-(10a+10b)
dla a=1/5
b=2
15a+9b-10a-10b=5a-b
5*1/5-2=1-2=-1
b) 2-10(2y-x)+2(-y+4x)
dla x=-1
y=-0.1
2-20y+10x-2y+8x=2-22y+18x
2-22*-0,1+18*-1=2-(-2.2)+(-18)=4,2-13,8
c) -2(-3x-y)-3x(1+y)
dla x=2
y=1/4
6x+2y-3x-3xy=3x+2y-3xy
3*2+2*0,25-3*2*0,25=6+0,5-1,5=5
d)-(6-3y)-(x-2y)-2(x+y)
dla x= -1
y= -1/3
-6+3y-x+2y-2x-2y=-6+3y-3x
-6+3*-1/3-3*-1=-6-1+3=8