Warm Sheep and Big Big Wolf start from two places 20 kilometers apart at the same time and walk towards each other. If the warm goat walks 4 kilometers per hour and Big Big Wolf walks 6 kilometers per hour, how many hours will it take for the two to meet?
暖羊羊，灰太狼两人分别从相距20千米的两地同时出发相向而行，假如暖羊羊每小时行走4千米，灰太狼每小时走6千米，两人几小时后相遇？
<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">20 / 10</gadget>
<output>2</output>

<result>2</result>