To solve this problem we will use the equations of kinetic and mechanical energy.
We start for the first angle where the given angle is 36.5 ° and the acceleration is zero.
The force equations would be given by:

Where
is coefficient of friction (static)
If we make a sum of forces in the direction in which the block moves we will have the SinΘ Component and that of the friction force, so

solving for the coefficient,

We apply the same consideration for the angle of 30.5°, then we know that the coefficient (dinamic) is
