3 5/14 - 1 - 6/7 = 42/14 - 1 - 6/7
= 3 - 1 - 6/7
= 2 - 6/7
= (2 * 7 - 6) / 7
= (14 - 6) / 7
= 8 / 7
= 1 1/7