The distance between A and B is 66 kilometers. A and C walk from A to B, and B walks from B to A. A travels 12 kilometers per hour, B travels 10 kilometers per hour, and C travels 8 kilometers per hour. The three start at the same time, how many hours later, B just reaches the midpoint of the distance between A and C?
A、B两地相距66千米，甲、丙两人从A地向B地行走，乙从B地向A地行走．甲每小时行12千米，乙每小时行10千米，丙每小时行8千米．三人同时出发，多少小时后，乙刚好走到甲、丙两人距离的中点？
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<gadget id="calculator">8 + 6 + 6</gadget>
<output>20</output>

<gadget id="calculator">66 / 20</gadget>
<output>33/10 = around 3.3</output>

<result>33/10 = around 3.3</result>