The teacher brought some money to the bookstore to buy review materials. If you buy all "Chinese Review Test Questions", you can buy 30 copies, and if you buy all "Mathematics Review Materials", you can buy 20 copies. How many sets can you buy with your money?
老师带了一些钱去书店买复习资料，如果全买《语文复习试题》可以买30本，全买《数学复习资料》可以买20本，如果一本语文一本数学为一套，线都带的钱可以买几套？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/30) + (1/20)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / (1/12)</gadget>
<output>12</output>

<result>12</result>