A batch of wood can be used to make 20 desks and 30 chairs. How many sets of such desks and chairs can be made with this batch of wood?
一批木料，做课桌可以做20张，做椅子可以做30把．这批木料可以做几套这样的课桌椅？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

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

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

<result>12</result>