0.8÷(5/4×1.25)÷(0.64-1/25)+1.2×0.5÷4/5
=0.8÷(5/4×5/4)÷(0.64-0.04)+6×5/4
=4/5÷(25/16)÷(3/5)+6×5/4
=4/5×(16/25)×(5/3)+6×5/4
=64/75+15/2
=128/150+1125/150
=1253/150