3分之4:1.6 

=4/3:8/5

=(4/3x15):(8/5x15)

=20:24

=5:6

6分之5:8分之5 

=(5/6x24)：(5/8x24)

=20:15

=4:3

5分之3km:800m

=600m:800m

=600:800

=3:4