On May 1 this year, Chen Peng's family set off from Dongguan and traveled to Qingyuan by car. Travel 64 kilometers per hour and arrive in 5 hours. Return on the same road on May 2. If it takes 4 hours to return to Dongguan, how many kilometers per hour should I drive? (Solve with ratio)
今年5月1日，陈鹏一家从东莞出发，自驾车到清远旅游．每小时行驶64千米，5小时到达．5月2日原路返回，如果要4小时回到东莞，每小时要行驶多少千米？(用比例解)
<gadget id="calculator">64 * 5</gadget>
<output>320</output>

<gadget id="calculator">320 / 4</gadget>
<output>80</output>

<result>80</result>