At 10 am on December 1, there is 1 wolf, 22 cats, and 400 mice in the house. Every day at 12 o'clock in the daytime, the wolf will eat 2 cats, and every night at 12 o'clock, each cat will eat 1 mouse. At 10 o'clock on December 22, how many mice were there in the house? (assuming each animal will not breed during this time)
12月1日上午10点时，屋子里有1匹狼，22只猫，400只老鼠，每天白天12点时，狼会吃掉2只猫，每天夜里12点时，每只猫会吃掉1只老鼠．12月22日10点时，屋子里还有多少只老鼠．(假设每种动物在这段时间内都不会繁殖)
<gadget id="calculator">22 - 2</gadget>
<output>20</output>

<gadget id="calculator">20 + 0</gadget>
<output>20</output>

<gadget id="calculator">11 / 2</gadget>
<output>11/2 = around 5.5</output>

<gadget id="calculator">20 * (11/2)</gadget>
<output>110</output>

<gadget id="calculator">400 - 110</gadget>
<output>290</output>

<result>290</result>