The toy counter of Limin Supermarket bought 150 yo-yos and sold them for 25 yuan each. After selling all of them, they made a profit of 600 yuan. What is the purchase price of each yo-yo?
利民超市玩具柜台购进了150个溜溜球，每个卖25元，全部卖出后赚了600元，每个溜溜球的进价是多少元？
<gadget id="calculator">25 * 150</gadget>
<output>3_750</output>

<gadget id="calculator">3_750 - 600</gadget>
<output>3_150</output>

<gadget id="calculator">3_150 / 150</gadget>
<output>21</output>

<result>21</result>