Village A and village B were 56 km apart.

At 10.00 a.m. , John rode a horse from village A to village B at an average speed of 7 km/h.

At the same time , Mary drove a car from village B to village A.

They passed each other 6 h later.

If both Mary and John travelled on the same road , find Mary's average speed .

Notes to student:

1. Leave your answer as a mixed number in the form of A B/C where it is A`B/C`