Answer:
Her monthly principal payment is D: $579.81 and monthly interest payment is 0.4375.
Explanation:
Ok, in order to calculate the monthly principal and interest payment, we can use this relatively simple equation. The equation is:

Where variables represent the following:
M is your monthly payment.
P is your principal.
r is your monthly interest rate, calculated by dividing your annual interest rate by 12.
n is your number of payments (the number of months you will be paying the loan throughout the 30 years)
Then, in this case:
M=?
P=$105,000
5.25%=5.25/100=0.0525, then


So,
$
Solving this,
$
$
$
$
Her monthly principal payment is $579.81.