The school organizes excursions. The original plan was to walk 3.5 kilometers per hour and reach the destination in 5 hours. How many kilometers per hour on average will the original distance be covered in 2.5 hours? (To solve the equations, write out the equivalent relationship first)
学校组织远足活动．原计划每小时走3.5千米，5小时到达目的地．实际2.5小时走完原定路程，平均每小时走多少千米？(列方程解答，先写出等量关系)
<gadget id="calculator">3.5 * 5</gadget>
<output>17.5</output>

<gadget id="calculator">17.5 / 2.5</gadget>
<output>7</output>

<result>7</result>