The box is in equilibrium, so Newton's second law says
n + (-w) = 0
65 N + (-f ) = 0
where n denotes the magnitude of the normal force, w denotes the weight of the box, and f denotes the magnitude of the friction force.
The box has a weight of
w = (25 kg) (9.80 m/s²) = 245 N
so n = 245 N, too.
The friction force has magnitude
f = 65 N
and is proportional to the normal force by a factor of µ, the coefficient of kinetic friction. So we have
65 N = µ (245 N) → µ ≈ 0.26
