A bus carries a total of 50 passengers. Each ticket is 1 yuan for cash and 0.5 yuan for each ticket. The conductor finally calculated a total of 41 yuan for the sale. How many people bought tickets with the card?
一辆公交车共载乘客50人，用现金买票每张1元，刷卡买票每张0.5元．售票员最后统计出共卖得41元钱，用卡买票的有多少人？
<gadget id="calculator">50 - 41</gadget>
<output>9</output>

<gadget id="calculator">1 - 0.5</gadget>
<output>0.5</output>

<gadget id="calculator">9 / 0.5</gadget>
<output>18</output>

<result>18</result>