Two basic ways in which to do this problem:
1. Find and apply the LCD.
2. Convert all of the given numbers to their decimal form, to 2 or 3 places only.
Try #2 first:
5/6 = 0.83
4/5 = 0.80 is not between 5/6 and 1. Reject it.
4/7 = 0.57 Reject
6/7 = 0.86 This is between 5/6 and1. This is the answer.
