Calculate Current Through Battery Connected to Resistor

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Homework Statement



The voltmeter is removed (previous question was a voltmeter connected to a battery and it reads 12 V) and a resistor of 21 ohm is connected to the battery. What is the current (I) through the battery?


Homework Equations



emf=V
I=emf/(R+r)

The Attempt at a Solution



I tried to do I=12V/21 ohm but I don't know how to find R. When I entered the solution of that, it said to include the internal resistance of the battery, but I don't know the current of the battery so I can't use emf=IR to find R.
 
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Is there an answer in the back of the book to compare to?
 
haha nevermind. I was having trouble because I didn't have enough information, but I just didn't see where it was written. Thanks for your help anyway!