The school has a sum of money, the money to buy a desk is (1/30), and the money to buy a chair is (1/60). If you buy desks and chairs as a set, how many sets can you buy?
学校有一笔钱，买一个课桌的钱是这笔钱的(1/30)，买一把椅子的钱是这笔钱的(1/60)．如果成套买课桌椅，可以买多少套？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/30) + (1/60)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / (1/20)</gadget>
<output>20</output>

<result>20</result>