The distance between the two places is 420 km. A train of passenger cars and a train of trucks depart from A and B at the same time. It is known that the bus travels 80 km per hour, and the speed ratio of the bus and the truck is 4:3. How long does it take for the two cars to meet each other? ? (column equation)
两地相距420千米，一列客车和一列货车同时从甲、乙两地相对开出，已知客车每小时行80千米，客车与货车速度比是4：3，两车经多少小时才能相遇？(列方程)
<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">80 / (4/3)</gadget>
<output>60</output>

<gadget id="calculator">80 + 60</gadget>
<output>140</output>

<gadget id="calculator">420 / 140</gadget>
<output>3</output>

<result>3</result>