In the past, it took about 3 hours for a ship to pass through the five-level ship lock of the Three Gorges Dam. After the ship lift was put into use in 2004, the time for passing the lock was reduced by 70%. Hour?
过去船只经过三峡大坝的五级船闸大约要用3小时，2004年升船机投入使用后，过闸时间比原来减少了70%，使用升船机后，船只经过三峡大坝大约要用多少小时？
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">3 * (3/10)</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>