1) a + b - c = 1/3 + 4/5 - 1/12 = 20/60 + 48/60 - 5/60 = 63/60 = 21/20
2) a - b + c = 2/7 - 1/6 + 1/9 = 18/63 - 7/63 + 7/63 = 18/63 = 6/21 = 2/7
1) a + b - c = 1/3 + 4/5 - 1/12 = 20/60 + 48/60 - 5/60 = 63/60 = 21/20
2) a - b + c = 2/7 - 1/6 + 1/9 = 18/63 - 7/63 + 7/63 = 18/63 = 6/21 = 2/7