2/3 * 12 = 8
10 / 4/15 = 10*15 /4 = 150/4 = 37 2/4 = 37.5
4/9 / 7/10 / 8/3 = 5/21
2/11 + 3/8 + 4/11 +6/11 +5/8 = (2/11 +4/11 +6/11) + (3/8 + 5/8) = 12/11 +8/8 = 1 1/11 +1 = 2 1/11
11/36 *17 - 5 *9/16 = 187/36 - 45/16 = 748/144 - 405/144 = 343/144 = 2 55/144