There are three kinds of tickets for children's park and playground, A ticket is 7 yuan, B ticket is 4 yuan, and C ticket is 2 yuan. One day, a total of 85 tickets were sold in the amusement park, with a revenue of 500 yuan, among which A ticket was sold 31 more than B ticket. So how many tickets are sold.
儿童公园游乐场的门票分三种，甲票7元，乙票4元，丙票2元．一天，游乐场共售出了85张门票，收入500元，其中甲票比乙票多售出31张．那么甲票售出多少张．
<gadget id="calculator">25 + 31</gadget>
<output>56</output>

<result>56</result>