3/4÷0.8 = 0.75÷0.8 = 75/80 = 15/16
3/4÷0.8 = 3/4÷（4/5）=（3/4）×（5/4）= 15 / 16
3/4÷0.8 = 3÷（4×0.8）= 3÷3.2 = 15/16