a$)$ A multiplate clutch has three discs on the driving shaft and $2$ discs on the driven shaft, providing four pairs of contact surfaces, each of $240$mm external diameter and $120$mm internal diameter. Assuming uniform pressure, determine the total spring load pressing the plates together to transmit $25$kW at $1575$RPM$.$ Take p as $0\mathrm{.}3$

b$)$ If there are $6$ springs, each of stiffness $13$k$/$m and each of the contact surfaces has worn away by $1\mathrm{.}25$mm$,$ what is the maximum power that can be transmitted at the same RPM$,$ assuming uniform wear and the same coefficient of friction?