Let x represent the number of magnets and y represent the number of key chains.
She must purchase at least 24 gifts but has to spend less than $20.
x + y >= 24
0.5x + y < 20
An appropriate solution is x=20 and y=5. They satisfy both inequalities:
x + y = 25 so it is more than 24.
0.5x + y = 15 so it is less than 20.