please specify the formula :)

4. Three blocks of masses 10.0 kg, 5.00 kg, and 3.00 kg are connected by light strings that pass over frictionless pulleys as shown. The acceleration of the 5.00-kg block is 2.00 m/s2 to the left, and the surfaces are rough. Find (a) the tension in each string and (b) the coefficient of kinetic friction between blocks and surfaces. (Assume the same uk for both blocks that are in contact with surfaces.) 5.00 kg To 3.00 kg 10.0 kg 25.00 The coefficient of friction between the block and plane is 0.20. Determine the accelerations and the tensions. 2.0 kg 5.0 kg 250 ............ 12.0 kg