Найти значение выражения ( 1/2 +1/4 - 2/5 ) :4/5 , 3/4: ( 1 - 1/4+ 3/8 ) , ( 1/3 +1/4) : (2 -5/6 )

1) (1/2 + 1/4 - 2/5) : 4/5 = (10/(2 * 10) + 5/(4 * 5) - (4 * 2)/(5 * 4)) * 5/4 = (10/20 + 5/20 - 8/20) * 5/4 = (10 + 5 - 8)/20 * 5/4 = 7/20 * 5/4 = 7/16;

Ответ: 7/16.

2) 3/4 : (1 - 1/4 + 3/8) = 3/4 : (8/8 - 2/8 + 3/8) = 3/4 : (8 - 2 + 3)/8 = 3/4 : 9/8 = 3/4 * 8/9 = (3 * 8)/(4 * 9) = 2/3;

Ответ: 2/3.

3) (1/3 + 1/4) : (2 - 5/6) = (4/12 + 3/12) : (12/6 - 5/6) = 7/12 : 7/6 = 7/12 * 6/7 = (7 * 6)/(12 * 7) = 1/2;

Ответ: 1/2.