The total amount of money obtained from selling 4 units of a certain commodity at a price higher than the purchase price of 5 yuan is equal to the total amount of money obtained from selling 3 units at a price higher than the purchase price of 20 yuan. How much is it.
某种商品以高于进价5元的价格卖出4个所得的总钱数，与以高于进价20元的价格卖出3个所的总钱数相等，这种商品每个进价是多少元．
<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">60 - 20</gadget>
<output>40</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">40 / 1</gadget>
<output>40</output>

<result>40</result>