Mathematics 2 / 7 times (- 5 / 12) - 3 / 7 times 5 / 12 + 5 / 7 times 17 / 12

Mathematics 2 / 7 times (- 5 / 12) - 3 / 7 times 5 / 12 + 5 / 7 times 17 / 12

The first two items merge = 5 / 7 times 5 / 12 of negative, and then merge with the third item = 5 / 7 times 12 / 12 = 5 / 7