Tim buys a book of esoteric words.  He learns 10 words from it a day.  In 2 years the book has increased the number of words he knows by 50%.  How many words did he know originally?
In 2 years there are 365*2=
<gadget id="calculator">365*2</gadget>
<output>730</output>
730 days.
So he has learned 730*10=
<gadget id="calculator">730*10</gadget>
<output>7_300</output>
7300 words.
He knew 1/.5=2 times that number of words before the book.
So he knew 7300*2=
<gadget id="calculator">7300*2</gadget>
<output>14_600</output>
14600 words before.

<result>14_600</result>