There are a total of 20 pieces of 5 yuan and 10 yuan yuan, and the total is 175 yuan. How many pieces of 5 yuan yuan are there?
有5元和10元的人民币共20张，一共是175元，5元的人民币有多少张．
<gadget id="calculator">10 * 20</gadget>
<output>200</output>

<gadget id="calculator">200 - 175</gadget>
<output>25</output>

<gadget id="calculator">10 - 5</gadget>
<output>5</output>

<gadget id="calculator">25 / 5</gadget>
<output>5</output>

<result>5</result>