12/15= 4/5
32/48= 8/12= 2/3
12/15 = (12 ÷ 3) / (15 ÷ 3) = 4/5
32/48 = (32 ÷ 16) / (48 ÷ 16) = 2/3
9•2•3/8•18•21=2•1•1/4•2•7=1/4•7=1/28
в 3 не впевнена
