Найдите значение выражений 2 4/5-1 2/3, 7 1/6+2 1/4, 11/15-2/5, 3/4+3/14

Найдём значение выражений, целую часть прибавляем к целой, а дробную к дробной части:

1) 2 4/5 - 1 2/3 = 2 - 1 + 4/5 - 2/3 = 1 + (4 * 3)/(5 * 3) - (2 * 5)/(3 * 5) = 1 + 12/15 - 10/15 = 1 + (12 - 10)/15 = 1 + 2/15 = 1 2/15;

2) 7 1/6 + 2 1/4 = 7 + 2 + 1/6 + 1/4 = 9 + (1 * 4)/(6 * 4) + (1 * 6)/(4 * 6) = 9 + 4/24 + 6/24 = 9 + (4 + 6)/24 = 9 + 10/24 = 9 + 5/12 = 9 5/12;

3) 11/15 - 2/5 = 11/15 - (2 * 3)/(5 * 3) = 11/15 - 6/15 = (11 - 6)/15 = 5/15 = 1/3.

4) 3/4 + 3/14 = (3 * 7)/(4 * 7) + (3 * 2)/(14 * 2) = 21/28 + 6/28 = (21 + 6)/28 = 27/28.