(3 1/4 + 2 1/6) : 2 3/5 - 2/3 * 2 1/4 + 5 1/6 = 5 39/52,
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 = 325/156 = 2 13/156,
3) 2/3 * 2 1/4 = 2/3 * 9/4 = 3/2 = 1 1/2,
4) 2 13/156 - 1 1/2 = (2 - 1) + (13/156 - 1/2) = 1 + (13/156 - 78/156) =
= 1 - 65/156 = 156/156 - 65/156 = 91/156,
5) 91/156 + 5 1/6 = 5 + (91/156 + 26/156) = 5 + 117/156 = 5 + 39/52 = 5 39/52