4 51: 1целую 2 17 * 57 64

4/51 : 1 2/17 * 57/64 = 1/16

1) 4/51 : 1 2/17 = 4/51 : 19/17 = 4/51 * 17/19 = (4*1)/(3*19) = 4/57
2) 4/57 * 57/64 = 4/64 = 1/16