Two models, $R_1=14\mathrm{.}11+0\mathrm{.}83t$ and $R_2=14\mathrm{.}11+0\mathrm{.}33t,$ are given for

revenue $(in$ billions $of$ dollars per year$)$ for a large corporation. Both models are

estimates $of$ revenues for $2007$ through $2011,$ with $t=7$ corresponding $to2007.$

Which model $is$ projecting the greater revenue? How much more total revenue does

that model project over the five$-$year period?