This looks like a school homework.
I assume that it is a parallel interface with one word clocked every clock cycle when a data strobe is active. One strobe for writing and one for reading.
You must know how the data strobes can be distributed within the specified intervals. I assume that all distributions are allowed, otherwise they would have to specify it in the question.
The worst case would be to clock in data as early as possible and out as late as possible.
For each clock cycle, count how many words must be buffered in the FIFO.
Come back when you have done some thinking, and maybe you can get some more clues.