(3乘4乘5)除以(0.6乘0.8乘0.25)=(3÷0.6)×(4÷0.8)×(5÷0.25)=(1÷0.2)×(1÷0.2)×(1÷0.5)=(1÷1/5)×(1÷1/5)×(1÷1/2)=(1×5)×(1×5)×(1×2)=5×5×2=20
