Вычислите (№ 538-540). 538. a) 2 4/13 + 2/13; б) 2 4/13 + 1 2/13; в) 2 4/13 + 10/13; г) 2 4/13 + 1 10/13 539. a) 1 1/8 + 3/8; б) 1 1/8 + 2 3/8; в) 1 1/8 + 7/8; г) 1 1/8 + 2 7/8 540. a) 3 4/19 + 8/19; б) 3 4/19 + 2 8/19; в) 3 4/19 + 18/19; г) 3 4/19 + 2 18/19.

**538.** a) (2\frac{4}{13} + \frac{2}{13} = 2\frac{4+2}{13} = 2\frac{6}{13}) б) (2\frac{4}{13} + 1\frac{2}{13} = (2+1) + \frac{4+2}{13} = 3\frac{6}{13}) в) (2\frac{4}{13} + \frac{10}{13} = 2\frac{4+10}{13} = 2\frac{14}{13} = 2 + 1\frac{1}{13} = 3\frac{1}{13}) г) (2\frac{4}{13} + 1\frac{10}{13} = (2+1) + \frac{4+10}{13} = 3\frac{14}{13} = 3 + 1\frac{1}{13} = 4\frac{1}{13}) **539.** a) (1\frac{1}{8} + \frac{3}{8} = 1\frac{1+3}{8} = 1\frac{4}{8} = 1\frac{1}{2}) б) (1\frac{1}{8} + 2\frac{3}{8} = (1+2) + \frac{1+3}{8} = 3\frac{4}{8} = 3\frac{1}{2}) в) (1\frac{1}{8} + \frac{7}{8} = 1\frac{1+7}{8} = 1\frac{8}{8} = 1+1 = 2) г) (1\frac{1}{8} + 2\frac{7}{8} = (1+2) + \frac{1+7}{8} = 3\frac{8}{8} = 3+1 = 4) **540.** a) (3\frac{4}{19} + \frac{8}{19} = 3\frac{4+8}{19} = 3\frac{12}{19}) б) (3\frac{4}{19} + 2\frac{8}{19} = (3+2) + \frac{4+8}{19} = 5\frac{12}{19}) в) (3\frac{4}{19} + \frac{18}{19} = 3\frac{4+18}{19} = 3\frac{22}{19} = 3 + 1\frac{3}{19} = 4\frac{3}{19}) г) (3\frac{4}{19} + 2\frac{18}{19} = (3+2) + \frac{4+18}{19} = 5\frac{22}{19} = 5 + 1\frac{3}{19} = 6\frac{3}{19}) **Ответ:** 538. a) 2 6/13; б) 3 6/13; в) 3 1/13; г) 4 1/13 539. a) 1 1/2; б) 3 1/2; в) 2; г) 4 540. a) 3 12/19; б) 5 12/19; в) 4 3/19; г) 6 3/19