a$.$ The heat$($H$)$ produced by an electric current varies directly as the square of the applied voltage $($V$)$ and inversely as the resistance $($R$)$ of the wire. A voltage of $540$ V applied to a wire of resistance $40$ produced $1458$J of heat. Find

i$.$ An expression between H$,$ V and R$.$

ii$.$ The resistance that would produce $588$J of heat when the voltage is $420$V$.$