It takes 2 hours for a small car to travel from A to B, and 4 hours for a large cart to travel from B to A. The two cars depart from the two places at the same time and leave opposite to each other. After how many hours they meet.
小车从甲地到乙地要2小时，大车从乙地到甲地要4小时．两车分别从两地同时出发，相对开出，经过多少小时相遇．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) + (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / (3/4)</gadget>
<output>4/3 = around 1.333333</output>

<result>4/3 = around 1.333333</result>