To calculate the monthly payments for the original loan, we use the formula for calculating monthly mortgage payments:

$M = P \times \frac{r(1 + r)^n}{(1 + r)^n - 1}$

Where:

• $M$ is the monthly payment
• $P = 300,000$ is the loan amount
• $r = \frac{\text{APR}}{12} = \frac{6\%}{12} = 0.005$ is the monthly interest rate
• $n = 40 \times 12 = 480$ is the total number of monthly payments (40 years)

Step 1: Plug the values into the formula

$M = 300,000 \times \frac{0.005(1 + 0.005)^{480}}{(1 + 0.005)^{480} - 1}$

Let’s break down the calculation:

1. $(1 + 0.005)^{480}$: This calculates the compounding factor.
2. Multiply that result by $0.005$.
3. Divide by $(1 + 0.005)^{480} - 1$.

Once you compute this, you will get the monthly payment amount.

Let me know if you would like help calculating this manually or if you'd like me to guide you further!