11/4*1 1/5=? , 2 1/2*2 4/5=? , 2 2/7*1 1/8=? , 1 3/5*7 1/2=? , 2 1/7*2 2/15=? , 2 2/9 * 2 19/40=?

5/4•6/5=3/2=[1]1/2.
5/2•14/5=7.
16/7•9/8=18/7=[2]4/7
8/5•15/2=12.
15/7•32/15=32/7=[4]4/7
20/9•99/80=11/4=[2]3/4.

Вроде бы вот так:
1(1/4) * 1(1/5) = (5/4) * (6/5) = 3/2 = 1(1/2)
2(1/2) * 2(4/5) = (5/2) * (14/5) = 7
2(2/7) * 1(1/8) = (16/7) * (9/8) = 18/7 = 2(4/7)
1(3/5) * 7(1/2) = 4 * 3 = 12
2(1/7) * 2(2/15) = (15/7) * (32/15) = 32/7 = 4(4/7)
2(2/9) * 2(19/40) = (20/9) * (99/40) = 11/2 = 5(1/2)