57 - 28 = 60 - 30 = 30
48 + 36 = 50 + 40 = 90
(5 4/5 - 1 7/48 *2,4) : 1,5=1 1/60
1 7/48 = 55/48 2,4= 2 4/10 = 2 2/5= 12/5
55/48 * 12/5= 11/4 = 2 3/4
5 4/5 - 2 3/4 = приведем к общему знаменателю 20= 5 16/20 - 2 15/20= 3 1/20
3 1/20= 61/20 1,5= 3/2
61/20 : 3/2 =61/20 *2/3= 61/30= 2 1/30