There are a new batch of textbooks in the supermarket, among which there are 50 more exercise books than math books. There are 220 of them in total. How many exercise books are there?
超市新进一批本子，其中练习本比数学本多50本，它们一共有220本，练习本有多少本？
<gadget id="calculator">220 + 50</gadget>
<output>270</output>

<gadget id="calculator">270 / 2</gadget>
<output>135</output>

<result>135</result>