Mom bought 3 boxes of apples, each with 15 kilograms, and the total cost was 180 yuan. How much is the average price per kilogram?
妈妈买了3箱苹果，每箱15千克，一共用了180元，平均每千克多少元？
<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">180 / 45</gadget>
<output>4</output>

<result>4</result>