91:7
=(91÷7):(7÷1)
=13:1
0.625:8分之7
=8分之5:8分之7
=(8分之5×8):(8分之7×8)
=5:7
25:0.75
=(25×100):(0.75×100)
=2500:75
=(2500÷25):(75÷25)
=100:5
=(100÷5):(5÷5)
=20:1