7 1/4 - (2,5 + 2 1/3) = 2 целых 5/12
1) 2,5 + 2 1/3 = 2 1/2 + 2 1/3 = 2 3/6 + 2 2/6 = 4 5/6
2) 7 1/4 - 4 5/6 = 7 3/12 - 4 10/12 = 6 15/12 - 4 10/12 = 2 5/12
Пояснения
2,5 = 2 5/10 = 2 1/2 (дробь 5/10 сократили на 5)
1/2 = 3/6 - доп.множ. 3
1/3 = 2/6 - доп.множ. 2
1/4 = 3/12 - доп.множ. 3
5/6 = 10/12 - доп.множ. 2