a) (2 + 3\frac{1}{5} = 5\frac{1}{5})
б) (4\frac{1}{4} + 15 = 19\frac{1}{4})
в) (23\frac{12}{13} + 7\frac{2}{13} = 23 + 7 + \frac{12}{13} + \frac{2}{13} = 30 + \frac{14}{13} = 30 + 1\frac{1}{13} = 31\frac{1}{13})
г) (2\frac{2}{3} + 5\frac{2}{3} = 2 + 5 + \frac{2}{3} + \frac{2}{3} = 7 + \frac{4}{3} = 7 + 1\frac{1}{3} = 8\frac{1}{3})