How much is the product of 4.87 and 3.9 plus the sum of 2.8 less than the largest two-digit number?
4.87与3.9的积加上2.8的和，比最大的两位数少多少？
<gadget id="calculator">4.87 * 3.9</gadget>
<output>18.993</output>

<gadget id="calculator">18.993 + 2.8</gadget>
<output>21.793</output>

<gadget id="calculator">99 - 21.793</gadget>
<output>77.207</output>

<result>77.207</result>