In the 100-meter race, the little rabbit ran in 15 seconds, and the little monkey ran in 20 seconds. At this speed, if the little rabbit and the little monkey walk towards each other from both ends of the 100-meter runway at the same time, how many seconds can they meet?
百米赛跑，小兔15秒跑完，小猴20秒跑完．照这样的速度，如果小兔和小猴分别从百米跑道的两端同时相对而行，多少秒后可以相遇？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/15) + (1/20)</gadget>
<output>7/60 = around 0.116667</output>

<gadget id="calculator">1 / (7/60)</gadget>
<output>60/7 = around 8.571429</output>

<result>60/7 = around 8.571429</result>