$1.$ a$.)$ Determine the torque $($N$-$m$)$ produced at P$4$ if the force at P$1=300$kg$,$ given that P$1=4$ inches in diameter, P$2=10$ inches, P$3=3$ inches, P$4=12$ inches. If P$1$ rotates at $3500$ RPM$.$

b$.)$ What is the power produced at P$4,$ if the transmission efficiency of the system is only $89\%?$