Question 856403
Maybe a tree diagram.  If three pennies then she has 30 cents using dimes, quarters, or nickels, inclusive.


Not quite a tree diagram, but looking at some combinations which could give 30 cent value or other values...


Quarters______________Dimes____________Nickels___________Cents-Value
0_____________________0________________6_________________30
0_____________________1________________4_________________30
0_____________________2________________2_________________30
0_____________________3________________0_________________30
1___________________*You could work through these yourself.....
...


*Actually if using 1 quarter, the possible combinations becomes very quick to find.  1 quarter plus 1 nickel = 25 cents plus 5 cents = 30 cents.