7. Coffee costing 250 per kg …

cost of coffee=250 per kg. cost of chicory =75 per kg coffee: chicory 5:2 if the weight of mixture is 1 kg.

{tex}\begin{aligned} & \frac{5 \mathrm{x}+2 \mathrm{x}}{7}=1 \\ & \Rightarrow 7 \mathrm{x}=7 \\ & \Rightarrow \mathrm{x}=1 \\ & \therefore \text { weight of coffee }=\frac{5 \mathrm{x}}{7}=\frac{5}{7} \mathrm{~kg} \\ & \text { weight of chicory }=\frac{2 \mathrm{x}}{7}=\frac{2}{7} \mathrm{~kg} \\ & \text { cost of } \frac{5}{7} \mathrm{~kg} \text { coffee }=\frac{5}{7} \times 250=\frac{1250}{7} \\ & \text { cost of } \frac{2}{7} \mathrm{~kg} \text { chicory }=\frac{2}{7} \times 75=\frac{150}{7} \\ & \text { total cost of } 1 \mathrm{~kg} \text { mixture }=\frac{1250}{7}+\frac{150}{7} \\ & \text { cost price of } 1 \mathrm{~kg} \text { mixture }=\frac{1400}{7}=200 \text { Rs } \\ & \text { selling of } 1 \mathrm{~kg} \text { minute }=230 \mathrm{Rs} \\ & \text { gain or loss }=\frac{\text { SP }-\mathrm{CP}}{\text { CP }} \times 100=\frac{230-200}{200} \times 100 \\ & =\frac{30}{2}=15 \% \end{aligned}{/tex}

since its positive, the mixture was sold at a gain of 15%.