Answer:
a) 336 different committees are possible.
b) 56 different committees are possible.
Explanation:
Permutations:
is the number of different combinations of x objects from a set of n elements, given by the following formula.

Combinations:
The number of possible permutations of x elements from a set of n elements is given by the following formula:

In this question:

A) permutations

336 different committees are possible.
B) combinations

56 different committees are possible.