Решите дроби 2/5+7/15 2/5+9/10 2/5+3/8 2/5+1 1/5 2/5+2/9

2/5 + 7/15 = (2 * 3 + 7 * 1)/15 = (6 + 7)/15 = 13/15 ;2/5 + 9/10 = (2 * 2 + 1 * 10)/10 = (4 + 10)/10 = 14/10 = 7/5 = 1 2/5 ;2/5 + 3/8 = (2 * 8 + 3 * 5)/40 = (16 + 15)/40 = 31/40 ;2/5 + 1 1/5 = 2/5 + 6/5 = 8/5 = 1 3/5 ; 2/5 + 2/9 = (2 * 9 + 2 * 5)/45 = (18 + 10)/45 = 28/45.