Oscar wants to train for a marathon. He plans to add 2/3 of a mile each week until he reaches a 20-mile run. How many weeks before the marathon should he start training if he has already run 2 miles?
Oscar needs to increase his maximum running time from 20 - 2 = 
<gadget id="calculator">20-2</gadget>
<output>18</output>
18 miles.
Oscar will need a total of 18 / ( 2 / 3 ) = 
<gadget id="calculator">18/(2/3)</gadget>
<output>27</output>
27 weeks to prepare.

<result>27</result>