4 * 2/5 - 3/5 : 4/15 + 2 = 1 целая 7/20
1) 4 * 2/5 = 8/5 = 1 целая 3/5
2) 3/5 : 4/15 = 3/5 * 15/4 = (3*3)/(1*4) = 9/4 = 2 целых 1/4
3) 1 3/5 - 2 1/4 = 1 12/20 - 2 5/20 = - (1 25/20 - 1 12/20) = - 13/20
4) - 13/20 + 2 = 2 - 13/20 = 1 20/20 - 13/20 = 1 целая 7/20
Пояснения:
3/5 = 12/20 - доп.множ. 4
1/4 = 5/20 - доп.множ. 5
2 целых 5/20 = 1 целая 25/20
2 = 1 целая 20/20