APR: If the APR is 9, then what is the interest rate r?

[Tess]

This is the problem:

APR=12r

If the APR is 9 what is the interest rate (r)?

9=12r

What do I do from here and why? I already have the answer but don't understand the rules of how to procede.

Thank you!

 

[tkhunny]

Divide by 12?

 

[Tess]

Yes, but why. What is the rule I use to do this?

 

[jonboy]

Division Property - which states that if you divide on one side you divide on the other and the equation is balanced.

You also have: Subtraction, Addition, and Multiplication Property. This site has many: List of Properties

 

[Tess]

Ohh, that makes sense. So, if I devide both sides by 12 I get 3/4 (75%) =r.

Thank you!