and B are walking toward each other from AB at the same time. When A travels (1/5) of the whole distance, B travels 42 kilometers; when A travels the entire distance, B travels the whole distance (6/7 ). Find the length of the whole journey of AB.
甲、乙两人同时从AB两地相向而行，当甲行了全程的(1/5)时，乙行了42千米；当甲行完全程时，乙行了全程的(6/7)．求AB全程的长．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">42 / (1/5) / (6/7)</gadget>
<output>245</output>

<result>245</result>