1) 2 1/3 * 3/7 = 1
1 - 5/6 = 1/6
2) 1/9 * 1 5/6 = 11/54
1/9 * 1 1/6 = 7/54
11/54 + 7/54 = 1/3
3) 1 3/8 * 3/5 = 33/40
3/5 * 1/8 = 3/40
33/40 + 3/40 = 9/10
