The owner of a clothing store spends a certain amount of dollars on clothes. With this money, he can buy exactly 20 coats or 30 pairs of trousers. If he buys them as a set, how many sets of this kind of clothes can he buy with the money.
服装店老板用若干元买服装，用这些钱正好可以买20件上衣，或30条裤子，如果成套购买，用这些钱最多可以买这种服装多少套．
<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>