(3 1/4+2 1/6):2 3/5-2/3*2 1/4

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

1) 3 1/4 + 2 1/6 = (3 + 2) + (1/4 + 1/6) = 5 + (3/12 + 2/12) = 5 + 5/12 = 5 5/12,

2) 5 5/12 : 2 3/5 = 65/12 : 13/5 = 65/12 * 5/13 = 25/12 = 2 1/12,

3) 2/3 * 2 1/4 = 2/3 * 9/4 = 3/2 = 1 1/2,

4) 2 1/12 - 1 1/2 = 25/12 - 3/2 = 25/12 - 18/12 = 7/12