Answer:

3 2/7 + 4 1/3 (need to find the lowest common denominator, which is 21, in order to add these terms)

3 2/7 = 3 6/21

4 1/3 = 4 7/21

3 6/21 + 4 7/21 = 7 13/21

Now subtract this total from the original length of cloth:

15 - 7 13/21

= 7 8/21 meters remain