The distance between AB and AB is 405 kilometers. A car travels from A to B for 90 kilometers in 2 hours. At this speed, how many hours will it take to reach B?
AB两地相距405千米，一辆汽车从A地开往B地，2小时行了90千米，照这样的速度，再行多少小时可到达B地．
<gadget id="calculator">405 - 90</gadget>
<output>315</output>

<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<gadget id="calculator">315 / 45</gadget>
<output>7</output>

<result>7</result>