You're going to have to give more information than this. What is the scenario? Follow the template given when posting. Also, you're going to have to show an attempt. We do not just give answers.
there is not a lot more information it only gives me the acceleration and the mass of the the object across the flat surface. i tried the kinetic friction force but am not sure if i used the right formula and have no idea how to use the μk formula
Okay, in order to find the coefficient of kinetic friction you need to know the formula f=Fn*uk, where f is the friction force, Fn is the normal force, and uk is the coefficient of kinetic friction. When you write your net force equation (Fnet=ma) you will be able to substitute this equation in place of f and solve for uk.