Uncle Liu bought a batch of apples at a wholesale price of 2.8 yuan per kilogram, and sold them all at a price of 3.5 yuan per kilogram, earning a total of 98 yuan. How many kilograms does this batch of apples weigh?
刘叔叔以每千克2.8元的批发价购进一批苹果，以每千克3.5元的价格全部售完，共赚了98元．这批苹果有多少千克？
<gadget id="calculator">3.5 - 2.8</gadget>
<output>0.7</output>

<gadget id="calculator">98 / 0.7</gadget>
<output>140</output>

<result>140</result>