The school buys a towel for each athlete of the sports team. If you buy 30, you will have 120 yuan left. If you buy 35, you will have 20 yuan left. How much is each towel?
学校给体育队的运动员们每人买一条毛巾，如果买30条，还剩120元，如果买35条，还剩20元，每条毛巾多少钱？
<gadget id="calculator">120 - 20</gadget>
<output>100</output>

<gadget id="calculator">35 - 30</gadget>
<output>5</output>

<gadget id="calculator">100 / 5</gadget>
<output>20</output>

<result>20</result>