A) 
Let's start by writing the equation of the forces along the directions parallel and perpendicular to the incline:
Parallel:
 (1)
 (1)
where
m is the mass
g = 9.8 m/s^2 the acceleration of gravity

 is the coefficient of friction
 is the coefficient of friction
R is the normal reaction 
a is the acceleration
Perpendicular:
 (2)
 (2)
From (2) we find

And substituting into (1)

Solving for a,

B) 5.94 m/s
We can solve this part by using the suvat equation

where
v is the final velocity
u is the initial velocity
a is the acceleration
s is the displacement
Here we have
v = ?
u = 0 (it starts from rest)

s = 8.70 m
Solving for v,

 
        
             
        
        
        
Answer:
-0.80985201682
Explanation:
Couldn't you have used Google???
 
        
             
        
        
        
Answer:

towards right so it is -15 degree
Explanation:
Net force in forward direction due to all three is given as

here we know that





Similarly in Y direction we will have



Now the net force on the donkey is given as



Now direction of force is given as


 towards right so it is -15 degree
 towards right so it is -15 degree
 
        
             
        
        
        
Subtract all numbers to your answer