Пошаговое объяснение:
(3 1/4 + 2 1/6) : 2 3/5 - 2/3 : 4/9= 7/12
1) 3 1/4 + 2 1/6 = 13/4 + 13/6 = 39/12 + 26/12 = 65/12
2) 65/12 : 2 3/5 = 65/12 : 13/5 = 65/12 * 5/13 = 25/12
3) 2/3 : 4/9 = 2/3 * 9/4 = 3/2
4) 25/12 - 3/2 = 25/12 - 18/12 = 7/12
