Is there not a key? There should always be a key.

a) If each number in the leaves are single digit, then count each of them. I get 30.

b) I guess you mean shortest and longest? The shortest is 55 and the longest 98, if that follows what the key describes...

c) Oh, so these numbers represent the time, in months acts have been in the firm?

Then count everything below 80. You should get 15.