A car drives from place A to place B. The ratio of the distance traveled to the whole journey is 1:4, and after another 50 kilometers, it just reaches the midpoint. How many kilometers is the distance between A and B?
一辆汽车从甲地开往乙地，已行的路程与全程的比是1：4，再行50千米，刚好到达中点．甲乙两地间的路程是多少千米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">50 / (1/4)</gadget>
<output>200</output>

<result>200</result>