Answer:
6
Step-by-step explanation:
If we place no restrictions on the values of the variables, there are an infinite number of possible solutions.
In this scenario, it is reasonable to require all variables have non-negative integer values. That restricts the solutions to ...
(x, y, z) ∈ {(15, 20, 0), (12, 22, 1), (9, 24, 2), (6, 26, 3), (3, 28, 4), (0, 30, 5)}
There are 6 solutions to her problem.
