Can someone please help me understand question 7 and 8. Especially the equation part. Thank you ?

Each of the following boxes are in static equilibrium. Draw the forces acting on each of the boxes and setup the force tables. Then write the force equations for each of the following boxes. Then solve for the coefficient of friction. Use g = 9.8 m/s2 7) Tables Equations F = 50 N 53.130 4kg Each of the following boxes are NOT in static equilibrium. Setup the force tables for each of the following boxes. Then write the force equations for each of the following boxes. Find the acceleration of each of the following boxes. Use g = 9.8 m/s2 and a coefficient of friction of 0.2 8) Tables Equations F = 50 N 36.87 10 kg 9) 8 kg 4 kg