Mom bought 4.5 kilograms of apples and some grapes, and the total cost was 45.8 yuan. It is known that each kilogram of apples is 6.5 yuan. How much did you spend on grapes?
妈妈买了4.5千克苹果和一些葡萄，共花了45.8元，已知每千克苹果6.5元，买葡萄花了多少元？
<gadget id="calculator">6.5 * 4.5</gadget>
<output>29.25</output>

<gadget id="calculator">45.8 - 29.25</gadget>
<output>16.55</output>

<result>16.55</result>