Xiaogang went climbing on the weekend. It took him 15 minutes to climb from the foot of the mountain to the top of the mountain, and 10 minutes to return to the foot of the mountain by the same road from the top of the mountain. It is known that Xiaogang went up the mountain at a speed of 60 meters per minute. How far is it from the foot of the mountain to the top of the mountain? What was Xiaogang's speed when he returned?
周末小刚去爬山，他从山脚爬到山顶用了15分钟，从山顶原路返回山脚用了10分钟，已知小刚上山的速度是60米/分，从山脚到山顶有多远？小刚返回时的速度是多少？
<gadget id="calculator">60 * 15</gadget>
<output>900</output>

<gadget id="calculator">900 / 10</gadget>
<output>90</output>

<result>90</result>