Example $9\mathrm{.}3.$ A constant load of $300$ MW is supplied by two generators, $1$ and $2,$ for which the incremental fuel costs are $\frac{d{F}_1}{d{P}_1}=0\mathrm{.}10P_1+20R\frac{s}{M}Wh$;$\frac{d{F}_2}{d{P}_2}=0\mathrm{.}12P_2+15R\frac{s}{M}Wh$ with power $P$ in MW and cost F in Rs$/$hr$.$ Determine $($i$)$ the most economical division of load between the generators and $($ii$)$ the saving in Rs$/$day thereby obtained compared the equal load sharing the generators.