(12 5/12 + 1 2/3 - 3 8/6 + 2 3/4) : (2 1/2 * 2/5 - 7/9) =
12 5/12 + 1 2/3 = 12 × 12 + 5 = 149
3 8/6 + 2 3/4 = 3 × 6 + 8 = 26
149 - 26 = 123
2 1/2 * 2/5 = 2 × 2 + 1 = 5 = 5 × 2/5 = 10/5
10/5 - 7/9 = 55/45
(12 5/12 + 1 2/3 - 3 8/6 + 2 3/4) : (2 1/2 * 2/5 - 7/9) =
12 5/12 + 1 2/3 = 12 × 12 + 5 = 149
3 8/6 + 2 3/4 = 3 × 6 + 8 = 26
149 - 26 = 123
2 1/2 * 2/5 = 2 × 2 + 1 = 5 = 5 × 2/5 = 10/5
10/5 - 7/9 = 55/45