There are only 4 times as many red balloons as there are green balloons in the store. If 9 red balloons and 5 green balloons are sold every day, how many days later there will be 90 red balloons and 6 green balloons left.
商店里有红气球只数是绿气球只数的4倍，如果每天卖出红气球9只，绿气球5只，多少天后，红气球还剩90只，绿气球还剩下6只．
<gadget id="calculator">6 + 5</gadget>
<output>11</output>

<gadget id="calculator">66 / 11</gadget>
<output>6</output>

<result>6</result>