In the given circuit, the electric currents through $15\, \Omega$ and $6 \, \Omega$ respectively are

A force of \( (6x^2 - 4x + 3) \, \text{N} \) acts on a body of mass 0.75 kg and displaces it from \( x = 5 \, \text{m} \) to \( x = 2 \, \text{m} \). The work done by the force is