2/5 делить на 4
8/9 делить на 2
15/16 делить на 5
7/30 делить на 2

2/5 : 4 = 2/5 : 4/1 = 2*1/5*4 = 2/20 = 1/108/9 : 2 = 8/9 : 2/1 = 8*1/9*2 = 8/18 = 4/915/16 : 5 = 15/16 : 5/1 = 15*1/16*5 = 15/80 = 3/167/30 : 2 = 7/30 : 2/1 = 7*1/30*2 = 7/60

2/5:4/1= 2/5*1/4=2/20=1/108/9:2/1= 8/9*1/2=8/18=4/915/16:5/1=15/16*1/5=3/16*1*1=3/167/30:2/1=7/30*1/2=7/60