As a spacecraft approaches a planet, the rocket engines on it are fired (turned on) to slow it down so it will go into orbit around the planet.

As a spacecraft approaches a planet, the rocket engines on it are fired (turned on) to slow it down so it will go into orbit around the planet. The spacecraft's mass is 2,475 kg and the thrust (force) of the rocket engines is 405 N. If its speed must be decreased by 1,234 m/s, how long (in minutes) must the engines be fired? (Ignore the change in the mass as the fuel is burned.)

Please explain how you got this answer as I really want to understand it.