Can anyone give me solution please.?
73. Block A, with weight 3w,slides down an inclined plane
S of slope angle 37$°$ at a constant speed while plank B,
with weight w,rests on top of A.The plank is attached
by a cord to the walt.(a) Draw a diagram of all the forces
acting on block A. (b) If the coefficient of kinetic
friction is the same between A and B and between S and 
A,determine its value.

$$\begin{gathered} \left(\mathrm{a}\right) \frac{9}{20} \left(\mathrm{b}\right) \frac{1}{5} \\ \left(\mathrm{c}\right) \frac{3}{4} \left(\mathrm{d}\right) \frac{1}{4} \end{gathered}$$