The highway from Guang'an to Chengdu is about 276km long. The average speed of the bus is x km/h, and the driving speed is 27.6km less at the front 1.8 than at the rear 2.2. Could you please calculate the average speed of the bus?
广安到成都的高速公路长约276km．大客车平均速度是x千米/时，前1.8时比后2.2时少行驶了27.6km．请你计算大客车的平均速度？
<gadget id="calculator">1.8 + 2.2</gadget>
<output>4</output>

<gadget id="calculator">276 / 4</gadget>
<output>69</output>

<result>69</result>