To dig a small canal, team A will need 15 days to complete it alone, and team B will need 12 days to complete it alone. If the two teams dig from both ends at the same time, and the distance between the two teams is still 66 meters after 3 days, what is the total length of this canal?
挖一条小渠，甲队单独做需要15天完成，乙队单独做需要12天完成．如果两队从两端同时挖，3天后两队还相距66米，那么这条水渠全长多少米？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/15) + (1/12)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/20) * 3</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (9/20)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">66 / (11/20)</gadget>
<output>120</output>

<result>120</result>