Well since the speed is 250m/s and it travels for 1 minute(60 seconds) you can just multiply the 2 together.
<u>250</u> x 60s<u> </u> 1s <u> </u>The unit of seconds will cancel out which leaves you with 15 000 m <u> </u>Therefore the plane will travel 15 000 m in one minute <u> </u>