Coach Sun buys sportswear for the school sports team. If you buy 80 sets with the money you bring, you will have 440 yuan left; if you buy 90 sets, you will have 20 yuan left. How much is each set of sportswear.
孙教练给学校体育队买运动衣．带去的钱如果买80套，还剩下440元；如果买90套，还剩下20元．每套运动衣多少元．
<gadget id="calculator">440 - 20</gadget>
<output>420</output>

<gadget id="calculator">90 - 80</gadget>
<output>10</output>

<gadget id="calculator">420 / 10</gadget>
<output>42</output>

<result>42</result>