Final answer:
To replace the scheduled payments of $675 and $1255, the unknown payment at the focal date of 15 months from today would be $2110.
Step-by-step explanation:
To replace the scheduled payments of $675 due today and $1255 due in 9 months, you need to find two new payments that will match the total amount due. Let's call the unknown payment X. The given information states that a payment of $1815 is due 3 months from today, and another unknown payment is due 15 months from today. We can set up an equation:
$675 + $1255 = $1815 + X
Solving for X:
X = $2110
Therefore, the unknown payment at the focal date of 15 months from today is $2110.