5.278 Найдите сумму: a) 7 + 2 5/8; б) 9 1/9 + 20; в) 64 5/7 + 4 1/7; г) 7 5/7 + 4 1/7.

a) (7 + 2 \frac{5}{8} = 9 \frac{5}{8}) б) (9 \frac{1}{9} + 20 = 29 \frac{1}{9}) в) (64 \frac{5}{7} + 4 \frac{1}{7} = 68 \frac{6}{7}) г) (7 \frac{5}{7} + 4 \frac{1}{7} = 11 \frac{6}{7})