You bought 6.4 kg of bananas and spent a total of 16.64 yuan, and bought 2.7 kg of apples at a total cost of 4.59 yuan. How much more expensive per kilogram of bananas than per kilogram of apples?
买了6.4千克香蕉，共花费16.64元，买了2.7千克苹果，共花费4.59元，则每千克香蕉比每千克苹果贵多少钱？
<gadget id="calculator">16.64 / 6.4</gadget>
<output>2.6</output>

<gadget id="calculator">4.59 / 2.7</gadget>
<output>1.7</output>

<gadget id="calculator">2.6 - 1.7</gadget>
<output>0.9</output>

<result>0.9</result>