Mom goes to the supermarket and buys 5 kilograms of apples, pays the salesperson 40 yuan, and gets back 1.5 yuan. What is the price per kilogram of apples?
妈妈去超市买了5千克苹果，付给售货员40元，找回1.5元，每千克苹果的价钱是多少？
<gadget id="calculator">40 - 1.5</gadget>
<output>38.5</output>

<gadget id="calculator">38.5 / 5</gadget>
<output>7.7</output>

<result>7.7</result>