In the given question, there are several information's of immense importance. Using those given information's, it is easy to get to the required result. It is given that the mass of the box Ellie is pushing is 7 kg with a force of 25 newtons. the force of friction effecting the acceleration is 2.6 Newton.
We already know that
Force = mass * Acceleration
We also know that
Force = Force applied - Force of friction
= (25 - 2.6) Newton
= 22.4 Newton.
Now putting the value of force in the equation, we get
Force = Mass * Acceleration
22.4 = 7 * Acceleration.
Acceleration = 22.4/7
= 3.2 m/s^2
So the value of acceleration is 3.2 m/s^2
