The speed of the bullet train can reach 250 km/h, which is 50 km/h more than twice that of the express train, and the speed of the high-speed train is 50 km/h more than three times that of the express train. Find the speed of the high-speed rail.
动车的速度可达250千米/时，比快速列车的2倍还多50千米/时，高铁的速度比快速列车的3倍还多50千米/时．求高铁的速度．
<gadget id="calculator">250 - 50</gadget>
<output>200</output>

<gadget id="calculator">200 / 2</gadget>
<output>100</output>

<gadget id="calculator">100 * 3</gadget>
<output>300</output>

<gadget id="calculator">300 + 50</gadget>
<output>350</output>

<result>350</result>