A stationery store buys 50 erasers at a wholesale price of 0.3 yuan each, and then sells them at a retail price of 0.5 yuan. How much profit can they make when they are all sold out?
文具店以批发价购进每块0.3元的橡皮50块，然后按0.5元的零售价出售，全部售完可获利多少元？
<gadget id="calculator">0.5 - 0.3</gadget>
<output>0.2</output>

<gadget id="calculator">0.2 * 50</gadget>
<output>10</output>

<result>10</result>