45/12

45/12 = 3 9/12 = 3 3/4

a) 4 3/4 : 1 5/6 * 3

1) 4 3/4 = 19/4

2) 1 5/6 = 11/6

3) 19/4 : 11/6 = 19/4 * 6/11 = (19*6)/(4*11) = (19*3)/(2*11) = 57/22

4) 57/22 * 3 = 171/22 = 7 17/22

Ответ: 7 17/22