# Question #9a08d

##### 1 Answer

#### Answer:

#### Explanation:

There are two quantities which we do not know, and they are the starting amount of money, called P, and the rate of interest called r.

We have 2 different pieces of information involving P and r.

For compound interest:

(

Change the formula to make P the subject.

Make 2 equations from the information which is given:

The sum of money, P, is the same, therefore

Then

It is not necessary to find the value of r, so we can just substitute into the first equation: