A convoy transported a batch of supplies to the earthquake-stricken area in Sichuan. It was originally planned to travel 40 kilometers per hour and reach the disaster-stricken area in 7.5 hours. The actual driving was 10 kilometers longer than the original plan. Based on this calculation, how many hours earlier could it arrive at the disaster-stricken area?
某车队为四川地震灾区运送一批物资，原计划每小时行驶40千米，7.5小时可以到达灾区，实际每小时比原计划多行驶10千米，照这样计算，可以提前多少小时到达灾区？
<gadget id="calculator">40 + 10</gadget>
<output>50</output>

<gadget id="calculator">7.5 / 50</gadget>
<output>0.15</output>

<gadget id="calculator">40 * 0.15</gadget>
<output>6</output>

<gadget id="calculator">7.5 - 6</gadget>
<output>1.5</output>

<result>1.5</result>