A person sold an article and got a loss of 9%. If he sells it Rs. 51 more he would gained 8%. Find the C.P.

$\begin{array}{l}LetCP=x\\ SPofarticle=x\times \frac{91}{100}=0.91x\\ if he sold it rs 51 more he would gain 8\%\\ 2^{nd}SP=0.91x+51\\ gain=8\%\\ x\times \frac{108}{100}=1.08x\\ 1.08x=0.9x+51\\ 0.17x=51\\ x=300\end{array}$