A certain commodity is sold for 4 coins at a profit of 5 yuan each, which is the same as the price of 3 coins sold at a profit of 20 yuan each. How much is the cost of this commodity per unit?
某件商品按每个5元的利润卖出4个钱数，与按每个20元的利润卖出3个的钱数一样多，这种商品每个成本是多少元？
<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>