7.2×[(7.8+1/5)÷0.4]
=7.2×[(7.8+0.2)÷0.4]
=7.2×(8÷0.4)
=7.2×20
=144
(6.9-3.14)÷0.3×0.8
=3.76÷0.3×0.8
=(188/15)×(4/5)
=257/75