A tourist bus travels on the plain and the mountain for 2 hours, and finally reaches the top of the mountain. It is known that the speed of the tourist bus on the plain is 50 km/h, and the speed on the mountain is 30 km/h. How long is this journey?
一辆旅游车在平原和山区各行了2小时，最后到达山顶，已知旅游车在平原的速度是50千米/小时，在山区的速度是30千米/小时．这段路程有多长？
<gadget id="calculator">50 + 30</gadget>
<output>80</output>

<gadget id="calculator">80 * 2</gadget>
<output>160</output>

<result>160</result>