GATE Electrical Engineering (EE) 2015 Shift 1 Solved Paper

Consider the economic dispatch problem for a power plant having two generating units. The fuel costs in Rs/MWh along with the generation limits for the two units are given below:
${\mathit{C}}_1\left({\mathit{P}}_1\right)=0.01{\mathit{P}}_1^2+30{\mathit{P}}_1+10;100\mathit{M}\mathit{W}\le {\mathit{P}}_1\le 150\mathit{M}\mathit{W}$
${\mathrm{C}}_2\left({\mathit{P}}_2\right)=0.05{\mathit{P}}_2^2+10{\mathit{P}}_2+10;100\mathit{M}\mathit{W}\le {\mathit{P}}_2\le 180\mathit{M}\mathit{W}$
The incremental cost (in Rs/MWh) of the power plant when it supplies 200 MW is ___________