and B start from AB at the same time and walk toward each other. A's speed is 52 m/min, and B's speed is 70 m/min. The two meet at C. If A starts 4 minutes earlier and the speed remains the same, B speeds up. 20 meters per minute, the meeting point of the two people remains unchanged, how to find the distance of AB?
甲乙两人分别从AB同时出发相向而行，甲的速度是52米/分，乙的速度是70米/分，两人在C相遇，如果甲提前4分钟出发速度不变，乙速度加快了20米/分，两人相遇点不变，求AB的距离？
<gadget id="calculator">70 + 20</gadget>
<output>90</output>

<gadget id="calculator">70 / 90</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">1 - (7/9)</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">4 / (2/9)</gadget>
<output>18</output>

<gadget id="calculator">52 + 70</gadget>
<output>122</output>

<gadget id="calculator">18 * 122</gadget>
<output>2_196</output>

<result>2_196</result>