Cars A and B start from A and B respectively at the same time and drive toward each other. A travels 50 kilometers per hour, and B travels 40 kilometers per hour. A arrives at the midpoint 1 hour earlier than B. How long does it take for A to reach the midpoint?
甲、乙两车分别从A、B两地同时出发，相向而行，甲每小时行50千米，乙每小时行40千米，甲比乙早1小时到达中点．甲几小时到达中点？
<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">40 * (1/10)</gadget>
<output>4</output>

<result>4</result>