Xiao Ming practices long-distance running along a 28-kilometer-long ring road at a speed of 8 kilometers per hour. One hour after he set off, Xiao Liang had an urgent letter to deliver to him. Xiao Liang rode a bicycle at a speed of 12 kilometers per hour. How many hours would it take to deliver the urgent letter to Xiao Ming?
小明以每小时8千米的速度沿着一条长28千米的环形公路练习长跑．他出发1小时后，小亮有一封急信要交给他，小亮以每小时12千米的速度骑自行车，最快要多少小时能把急信交到小明手中．
<gadget id="calculator">8 * 1</gadget>
<output>8</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

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

<result>2</result>