a) 9+8×7-2=9+56-2=65-2=63
(9+8)×7-2=17×7-2=119-2=117
b) 9+8×(7-2)=9+8×5=9+40=49
(9+8)×(7-2)=17×5=85
c)7×43-29×4+86=301-116+86=185+86=271
(7×43-28)×4+86=(301-28)×4+86=273×4+86=1092+86=1178
