Answer: The required number of combinations is 10.
Step-by-step explanation: We are given to find the number of combinations that exists for the letters m, n, o, p, and q taken 3 at a time.
We know that
the formula for the combination of s objects taken r at a time is given by

For the given combination, we have 5 letters and we are to take 3 at a time.
So, s = 5 and r = 3.
Therefore, the required number of combinations is

Thus, the required number of combinations is 10.