A car travels 40 kilometers per hour from place A to place B, and it takes 7.5 hours to get there. Actually, it travels 90 kilometers in 2 hours. According to this calculation, how many hours will it take to complete the journey? (Solution by two methods of positive and negative proportions)
一辆汽车从甲地开往乙地，每小时行40千米，7.5小时可以到达，实际2小时行90千米．照这样计算，行完全程用多少小时？(用正、反比例两种方法解)
<gadget id="calculator">40 * 7.5</gadget>
<output>300</output>

<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<gadget id="calculator">300 / 45</gadget>
<output>20/3 = around 6.666667</output>

<result>20/3 = around 6.666667</result>