a) 9+7x-3x=4x+9
b) 3a+5+12a-7=3a+12a+5-7=15a-2
c) 8-4y-y-6=-4y-y+8-6=-5y+2
d) 2x+5(3x+4)=2x+15x+20=17x+20
e) 8a-(6a-2)=8a-6a+2=2a+2
f) 3(5-4x)+10=15-12x+10=-12x+15+10=-12x+25
g) 3+5y-4(2y+5)=3+5y-8y-20=5y-8y+3-20=-3y-17
h) 5(3b+4)-2(6-7b)=15b+20-12+14b=15b+14b+20-12=29b+8
