SOLUTION: You have a handful of quarters, nickels, and dimes that totals 75 cents. Make a table listing all possible combinations of coins.

I will assume that you necessarily have at least one of each
kind of coin.  (For instance, 3 quarters is not allowed, nor 
is 15 nickels, nor 7 dimes and 1 nickel.)  

If you have 1 quarter, you can have from 1 up through 4 dimes,
and the rest in nickels.  That's 4 ways.

If you have 2 quarters, you can have either 1 or 2 dimes and
the rest in nickels.  That's 2 more ways.

So there are a total of 4+2 or 6 combinations of coins you 
can possibly have:

               Number of    Number of      Number of
Combination#   Quarters       dimes         nickels
    1             1             1             8
    2             1             2             6
    3             1             3             4
    4             1             4             2
    5             2             1             3
    6             2             2             1

You might impress your teacher by showing her or him that
you can also make a TREE diagram for that problem,
like this:  (See if you can figure it out) 




Edwin