24/15=3*8/3*5=8/5 36/60=12*3/12*5=3/5 56/72=8*7/8*9=7/9 42/66=6*7/6*11=7/11 54/81=27*2/27*3=2/3 84/90=16*4/16*5=4/5
24/15=24:3, 15:3=8/5,