A car travels half way from A to B, stops for fuel for the first time, travels the remaining half, stops for fuel for the second time, and is still 50 kilometers away from B. What is the distance between A and B in kilometers?
一辆汽车从甲地开往乙地，行了全程的一半，第一次停下来加油，又行了剩下来的一半，第二次停下来加油，这时离乙地还有50千米，甲、乙两地相距多少千米．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">50 / (1/2) / (1/2)</gadget>
<output>200</output>

<result>200</result>