The track of the Guangming Elementary School playground is 400 meters long. It takes Xiao Ming 40 seconds to run a lap, and Xiao Liang 50 seconds to run a lap. The two start at the same time and walk opposite each other. How many seconds later will they meet? (please use two methods to answer)
光明小学操场跑道长400米，小明跑一圈需要40秒，小亮跑一圈需50秒，两人同时同地出发，相背而行，多少秒钟后相遇？(请用两种方法解答)
<gadget id="calculator">400 / 40</gadget>
<output>10</output>

<gadget id="calculator">400 / 50</gadget>
<output>8</output>

<gadget id="calculator">10 + 8</gadget>
<output>18</output>

<gadget id="calculator">400 / 18</gadget>
<output>200/9 = around 22.222222</output>

<result>200/9 = around 22.222222</result>