and B start from the bottom of a 700-meter-long hillside and run upwards at the same time, and return immediately when they reach the top of the slope. They both went uphill at different speeds, and their downhill speeds were twice as fast as their respective uphill speeds. B first reaches the top of the slope, immediately returns along the original road, and meets A at a distance of 70 meters from the top of the slope. When B reaches the bottom of the slope (note: the starting point), how many meters is A behind B?
A、B两人同时从700米长的山坡坡底出发向上跑，跑到坡顶立即返回．他们俩的上坡速度不同，下坡速度则是两人各自上坡速度的二倍．B首先到达坡顶，立即沿原路返回，并且在离坡顶70米处与A相遇．当B到达坡底(注：起点)时，那么A落后B多少米．
<gadget id="calculator">70 / 2</gadget>
<output>35</output>

<gadget id="calculator">700 + 35</gadget>
<output>735</output>

<gadget id="calculator">700 - 70</gadget>
<output>630</output>

<gadget id="calculator">735 / 630</gadget>
<output>7/6 = around 1.166667</output>

<gadget id="calculator">70 * (7/6) * 2</gadget>
<output>490/3 = around 163.333333</output>

<gadget id="calculator">700 - 70 - (490/3)</gadget>
<output>1_400/3 = around 466.666667</output>

<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">(1_400/3) * (6/7)</gadget>
<output>400</output>

<gadget id="calculator">700 - 400</gadget>
<output>300</output>

<result>300</result>