б)3/8+2 1/4 г)5 2/15+3 2/9 е)4 3/5+10 1/4

Вычислим значения выражений:

б) 3/8 + 2 1/4 = 3/8 + 2 + 1/4 = 2 + 3/8 + 2/8 = 2 + (3 + 2)/8 = 2 + 6/8 = 2 + 3/4 = 2 3/4; 

г) 5 2/15 + 3 2/9 = 5 + 2/15 + 3 + 2/9 = (5 + 3) + (2/15 + 2/9) = 8 + 2/15 + 2/9 = 8 + (2 * 9 + 2 * 15)/135 = 8 + (18 + 30)/135 = 8 + 48/135 = 8 + 16/45 = 8 16/45; 

е) 4 3/5 + 10 1/4 = 4 + 3/5 + 10 + 1/4 = (4 + 10) + (3/5 + 1/4) = 14 + 3/5 + 1/4 = 14 + (3 * 4 + 1 * 5)/20 = 14 + (12 + 5)/20 = 14 + 17/20 = 14 17/20.