(2 7/12 + 1,75) : 13 + 2,5 : 3 3/4 = 1
1) 2 7/12 + 1,75 = 2 7/12 + 1 9/12 = 3 16/12 = 4 1/3 = 13/3
2) 13/3 : 13 = 13/3 * 1/13 = 1/3
3) 2,5 : 3 3/4 = 5/2 : 15/4 = 5/2 * 4/15 = (1*2)/(1*3) = 2/3
4) 1/3 + 2/3 = 3/3 = 1
Пояснения:
1,75 = 1 целая 3/4 = 1 целая 9/12 - доп.множ. 3
4 целых 1/3 = (4*3+1)/3 = 13/3
2,5 = 25/10 = 5/2 - сократили на 2
3 целых 3/4 = (3*4+3)/4 = 15/4