X yuan per kilogram of apples, the first basket is 15 kilograms, and the second basket is 20 kilograms. How much is the price of the first basket less than that of the second basket?
每千克苹果x元，第一筐15千克，第二筐20千克，第一筐比第二筐少卖多少元．
<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<result>5</result>