Charlie's utility $isU(c,d,h)=4c+10d-d^2-4h,$ where $dis$ the number $of$ hours per day that $he$

spends driving around, $his$ the number $of$ hours per day spent driving around $by$ other people $in$

his home town, and $cis$ the amount $of$ money $he$ has left $to$ spend $on$ other stuff besides gasoline

and auto repairs. Gas and auto repairs cost $$\mathrm{.}50$ per hour $of$ driving. All the people $in$ Charlie's

home town have the same tastes.