2 3/5 : 6 1/15 + 1 1/14 - 1 39/73 * (5 5/7 - 5 1/16) = 1/2
1) 5 5/7 - 5 1/16 = 5 80/112 - 5 7/112 = 73/112
2) 2 3/5 : 6 1/15 = 13/5 : 91/15 = 13/5 * 15/91 = 1/1 * 3/7 = 3/7
3) 1 39/73 * 73/112 = 112/73 * 73/112 = 1
4) 3/7 + 1 1/14 = 6/14 + 1 1/14 = 1 7/14 = 1 1/2
5) 1 1/2 - 1 = 1/2