A car travels on a plain and a mountain at speeds of 50 km/h and 30 km/h respectively, travels on the plain and mountain for 2 hours, and finally arrives at the destination. How long is this journey?
一辆汽车在平原和山区速度分别是50千米/时和30千米/时，在平原和山区各行了2小时，最后到达目的地．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>