Answer:
The principal must be = $8991.88
Step-by-step explanation:
Formula for compound interest is:

Where A is the amount after 't' years.
P is the principal amount
n is the number of times interest is compounded each year.
r is the rate of interest.
Here, we are given that:
Amount, A = $15000
Rate of interest = 13 % compounded quarterly i.e. 4 times every year
Number of times, interest is compounded each year, n = 4
Time, t = 4 years.
To find, Principal P = ?
Putting all the given values in the formula to find P.

So, <em>the principal must be = $8991.88</em>
So, and, but, but, or, nor, so. Im pretty sure this is correct.
So basically you are going to line up your equations (already done). Next, you will just add each term. So x + 3x = 4x, then 2y - 2y = 0 (we wouldn't put anything) then 7 - 3 = 4
So then we have all of our terms figured out and will have 4x = 4 then divide 4x by 4 to get x alone and then you will also divide the four that is by itself by four to equal one. So, your answer is x = 1. I hope that helps!
Multiply straight across (neg times a neg = a positive)
=28/81