(18-14*(2/5))/0.8
=(18-(28/5))/0.8
=((90-28)/5)/0.8
=(62/5)/(8/10)
=(62/5)*(10/8)
=(62/5)*(5/4)
=15.5
(18*(2/3)-4)*(7/9)
=(12-4)*(7/9)
=8*(7/9)
=56/9
=6又(2/9)