Xiao Ming bought 3 kilograms of pears and 3 kilograms of apples and paid 20.1 yuan in total, and 3.2 yuan for 1 kilogram of pears. How much is an apple per kilogram?
小明买了3千克梨和3千克苹果共付20.1元，1千克梨3.2元．每千克苹果多少元？
<gadget id="calculator">3.2 * 3</gadget>
<output>9.6</output>

<gadget id="calculator">20.1 - 9.6</gadget>
<output>10.5</output>

<gadget id="calculator">10.5 / 3</gadget>
<output>3.5</output>

<result>3.5</result>