After a plane flies from A to B at a speed of 250 kilometers per hour, it immediately turns around in the air, and flies back to A at a speed of 200 kilometers per hour. It takes 6.75 hours. What is the air distance between A and B in kilometers?
一架飞机以每小时250千米的速度从甲地飞往乙地后，立即在空中掉头，以每小时200千米的速度按原路飞回甲地，一共用了6.75小时．甲、乙两地的空中距离是多少千米？
<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">6.75 * (4/9) * 250</gadget>
<output>750</output>

<result>750</result>