There is a path around the pond. Xiao Ming and his father walked along this path together. They started from the same place, walked back to back, and met after 1 minute and 30 seconds. If Dad walks 6 meters per second and Xiao Ming walks 4 meters per second, how long is the path?
池塘的四周有一条小路，小明和爸爸一起沿着这条小路散步．他们从同一地点出发，背向而行，1分30秒后相遇．如果爸爸每秒走6米，小明每秒走4米，这条小路有多长？
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 90</gadget>
<output>900</output>

<result>900</result>