6.4 yuan per kilogram of fruit, mother bought 2.8 kilograms, got back 2.08 yuan, how much did mother pay?
每千克水果6.4元，妈妈买了2.8千克，找回2.08元，妈妈付了多少元？
<gadget id="calculator">6.4 * 2.8</gadget>
<output>17.92</output>

<gadget id="calculator">17.92 + 2.08</gadget>
<output>20</output>

<result>20</result>