The school pays a sum of money to buy prizes. You can buy 30 pens and 20 notebooks. Now you need to buy a set (one pen and one notebook). How many sets can you buy with this money?
学校出一笔钱买奖品，单买钢笔可以买30支，单买笔记本可以买20本，现在要成套购买，(一支钢笔配一个笔记本)，这笔钱可以买多少套？
<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>