1) 18 (1/3 - 1/9) = 18 1/3 - 18 * 1/9 = 6 - 2 = 4
2) (2-3/4-4/5) 20 = 2 20 - 3/4 20 - 4/5 20 = 40 - 15 - 16 = 9
1) 18 (1/3 - 1/9) = 18 1/3 - 18 * 1/9 = 6 - 2 = 4
2) (2-3/4-4/5) 20 = 2 20 - 3/4 20 - 4/5 20 = 40 - 15 - 16 = 9