Xiaojun rides a bicycle and travels 15 kilometers per hour, and his father drives five times faster than Xiaojun. How many kilometers does his father travel more per hour than Xiaojun?
小军骑单车每小时行15千米，爸爸开车的速度是小军的5倍，爸爸每小时比小军多行多少千米？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<result>60</result>