A friend of yours asks you for a loan of 2500 to invest in his toy sales business. You agree to apply a simple interest rate of 45% per year, and that the loan will be returned in 6 months. How much interest will he pay you?

1. Find the principal amount:
P = 2500
2. Find the annual interest rate:
R = 0.45
3. Find the time in years (6 months is 0.5 years):
T = 0.5
4. Use the simple interest formula:
I = P \times R \times T
5. Substitute the values into the formula:
I = 2500 \times 0.45 \times 0.5
6. Calculate the interest:
I = 562.50

The interest he will pay you is
562.50 .