Maximization of Utility Function Kabir’s utility is $U(c,d,h) = 2c+5d-d2-2h$, where $d$ is the number
  of hours per day that he spends driving around, $h$ is the number of
  hours per day spent driving around by the other people in his home
  town and $c$ is the amount of money he has left to spend on other
  stuff besides petrol and auto repairs. Petrol and auto repairs cost
  Rs.$50$ per hour of driving . All the people in Kabir’s home town have
  the same tastes. If each citizen believes that his own driving will
  not affect the amount of driving done by the others, they will all
  drive $D1$ hours per day. If they all drive the same amount,they would
  all be best off if each drove $D2$ hours per day, where
  
  (a) $D1=2$ and $D2=1$
  
  (b) $D1=D2=2$
  
  (c) $D1=4$ and $D2=2$
  
  (d) $D1=5$ and $D2=0$


I used the formula $$U=2(\bar{M}-50d)+5d-d^{2}-2h$$

and maximized w.r.t $d$ but it's giving an answer: $D1=\frac{5}{102}$

Any help will be appreited.
petrol and auto repairs cost 0.5 (not 50). This means $U=2(M−0.5d)+5d−d^2−2h$ and maximization w.r.t "$d$" gives $D1=2$. The formula for $D2$ is $U=2(M−0.5d)+5d−d^2−2d$, where "$h$" is replaced by "$d$". Maximization gives $D2=1$. Both formulas assume the budget constraint $0.5d+c=M$.
petrol and auto repairs cost 0.5 (not 50). This means $U=2(M−0.5d)+5d−d^2−2h$ and maximization w.r.t "$d$" gives $D1=2$. The formula for $D2$ is $U=2(M−0.5d)+5d−d^2−2d$, where "$h$" is replaced by "$d$". Maximization gives $D2=1$. Both formulas assume the budget constraint $0.5d+c=M$.