A $1-$inch storm event causes runoff which feeds into a stream. In the $1\mathrm{.}5-$mile reach of the stream, the initial inflow at t$1$ is $330$ cfs and the rate of outflow is $245$ cfs$.$ After $3$ hours, t$2,$ the inflow and outflow are $210$ cfs and $105$ cfs$,$ respectively. The storage at t$2$ has been observed to be $29\mathrm{.}5$ acre$-$feet. Assuming a linear change in flow rates over this time period, determine the change in storage in $3$ hours and the initial storage volume $($all in acre$-$ft$).$