15 * 5/6 = 5 * 5/2 = 25/2 = 12 1/2,

1 : 3/7 = 1 * 7/3 = 7/3 = 2 1/3,

2/3 * 12 = 2 * 4 = 8,

2/3 : 18 = 2/3 * 1/18 = 1/27,

8/27 * 36 = 32/3 = 10 2/3,

10 : 4/15 = 10 * 15/4 = 75/2 = 37 1/2