7. a) A
b) A
8. a) A
c) F
d) A
11. a) x=9*4:3=36:3=12
b) x=8*7:2=56:2=26
c) x=3*8:4=24:4=6
d) x=4*9:3=36:3=12
13. a) x=7*4:2-2=28:2-2+14-2=12
b) x=6*4:3-4=24:3-4=8-4=4
c) x=6*3:2+7=18:2+7=9+7=16
d) x=9*5:3+3=45:3+3=15+3=18
