A grocer purchased 80 kg of sugar at $\text{ ₹ }13.50$ per kg and mixed it with 120 kg sugar at $\text{ ₹ }16$ per kg. At what rate should he sell the mixture to gain 16%?

C.P. of 200 kg of mixture $=₹(80\times 13.50+120\times 16)$

                                            $=₹3000\text{. }$

$\text{ S.P. }=116\mathrm{\%}\text{ of Rs }3000=₹\left(\frac{116}{100}\times 3000\right)=₹3480$

$\therefore$ Rate of S.P. of the mixture $=₹\left(\frac{3480}{200}\right)\text{ per kg }$

                                                     $=₹17.40$ per kg