The monthly payment is $ 1892.392
Solution:
The formula for compound interest, including principal sum, is:

Where,
A = the future value of the investment
P = the principal investment amount
r = the annual interest rate (decimal)
n = the number of times that interest is compounded per unit t
t = the time the money is invested or borrowed for
From given,
p = 12500
t = 5 years

n = 12 ( compounded mothly )
Substituting the values we get,

What will her monthly payment be?

Thus monthly payment is $ 1892.392