For every increase of 100 meters in height in a certain area, the temperature drops by 0.8°C. Xiaoming and Xiaohong measured the temperatures at the foot of the mountain and the top of the mountain respectively at 6°C and -1.2°C. How many meters is the height of the mountain?
某地区高度每增加100米，气温下降0.8℃，小明和小红分别在山脚和山顶同测得气温分别是6℃和-1.2℃，山高多少米．
<gadget id="calculator">6 - (-1.2)</gadget>
<output>7.2</output>

<gadget id="calculator">7.2 / 0.8</gadget>
<output>9</output>

<gadget id="calculator">9 * 100</gadget>
<output>900</output>

<result>900</result>