1. **State the problem:** Rachel loaned Adam 8510 at an interest rate of 13% for 2 years. We need to find how much Adam will pay at the end of 2 years. 2. **Formula for simple interest:** $$I = P \times r \times t$$ where $I$ is the interest, $P$ is the principal amount, $r$ is the annual interest rate (in decimal), and $t$ is the time in years. 3. **Calculate the interest:** $$I = 8510 \times 0.13 \times 2$$ $$I = 8510 \times 0.26$$ $$I = 2212.60$$ 4. **Calculate the total amount to be paid:** $$A = P + I$$ $$A = 8510 + 2212.60$$ $$A = 10722.60$$ 5. **Answer:** Adam will pay **10722.60** at the end of 2 years.