Each card she sells cost $3.25.
y = 3.25s
y = 3.25(4) = 13
Each card she buys cost $5.50.
y = 5.25b
y = 5.25(7) = 38.5
She spent 38.5 dollars in total. However, you need to subtract the money she earned by the total cost.
38.5 - 13 = 25.5
She paid 25.5 dollars out of her own pocket, including the money she earned from selling cards she paid 38.5 dollars.
So the answer is "She spent $25.50"
Let me know if it's correct