Retired teacher Zhang walks slowly on the track of the track and field for exercise. He walks 75 meters per minute and plans to walk 3 times. It is known that the length of each track is 400 meters. How long will he be gone?
退休的张老师在田径场跑道上慢走锻炼，他每分钟走75米，打算走3圈，已知每圈跑道长400米．他走完要多久？
<gadget id="calculator">3 / 75</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">400 * (1/25)</gadget>
<output>16</output>

<result>16</result>