Найдите значение выражения 3/7×(1/4+4/9); 4/5-1/4:5/6.

1) 3/7 * (1/4 + 4/9) = 3/7 * (9/(4 * 9) + (4 * 4)/(4 * 9)) = 3/7 * (9/36 + 16/36) = 3/7 * (9 + 16)/36 = 3/7 * 25/36 = (3 * 25)/(7 * 36) = 25/(7 * 12) = 25/84;

Ответ: 25/84.

2) 4/5 - 1/4 : 5/6 = 4/5 - 1/4 * 6/5 = 4/5 - 6/20 = (4 * 4)/(4 * 5) - 6/20 = 16/20 - 6/20 = (16 - 6)/20 = 10/20 = 1/2;

Ответ: 1/2.