A tourist bus travels on a plain and a mountain for 3 hours each. It travels 50 kilometers per hour on the plain and 30 kilometers per hour on the mountain. How long is the distance?
一辆旅游车在平原和山区各行了3小时，在平原每小时行50千米，在山区每小时行30千米，这段路程有多长？
<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">150 + 90</gadget>
<output>240</output>

<result>240</result>