The two ports A and B are located upstream and downstream, and the distance between the two ports is 90 kilometers. Every day, two passenger ships A and B with the same speed set off from the two ports at the same time and head towards each other. At 8:00 this morning, ship A departed from A. A wooden box was dropped when starting from Hong Kong. After 2 minutes, the wooden box was 1 km away from Ship A. How many hours can ship B meet the wooden box after departure?
A、B两港位于上、下游，两港相距90千米，每天定时有甲、乙两艘船速相同的客轮从两港同时出发，相向而行，这天早上8时，甲船从A港出发时掉下一木箱，.2分钟后，木箱与甲船相距1千米．问乙船出发后几小时能遇上木箱？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / (1/30)</gadget>
<output>30</output>

<gadget id="calculator">90 / 30</gadget>
<output>3</output>

<result>3</result>