a) 14z+5z-3+8-9z=14z+5z-9z-3+8=10z+5
b) 8y-3+7y-2=8y+7y-3-2=15y-5
c) 6x-(-2x+4y)=6x+2x-4y=8x-4y
d) (6x+y)+(3x-6y)=6x+y+3x+6y=6x+3x+y+6y=9x+7y
e) -(5b-7)-(2b+3)=-5b+7-2b-3=5b-2b+7-3=3b+4
