1 1/4*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)