# Physics studying Forces help sos

Hello I have a test in 2 days and I know problems like this will be on it but I don’t understand it at all, could someone answer this question so I have something to work of off.

Three boxes are being pushed together on a surface with friction - A followed by B and then C. The first box has a mass of 25 kg while the second box has a mass of 45 kg and the third box he has a mass of 15 kg if an applied force of 275 N is applied on the box, the acceleration is measured at 1.4 m/s^2 [forward]

calculate the coefficient of kinetic friction and the reaction force of the box C on box B.

If someone could explain the process or order In how to get to the point of calculating. Like do I get the acceleration and from there the force then from there the weight. Which order do I calculate in?

I’m not asking for you to do the question I want to know how I get to the point where I can answer the question. What’s do I solve for first?

Thanks for anyone who helps in advance