Final answer:
The expression for how much Alexis spent is 5x, where x represents the amount of money Alexis spent on each shirt.
Step-by-step explanation:
The expression for how much Alexis spent can be written as 5x, where x represents the amount of money Alexis spent on each shirt. Since Alexis bought 5 shirts, she spent x dollars on each shirt, so the total amount she spent can be calculated by multiplying the cost of each shirt (x) by the number of shirts (5), which gives us 5x.