A milkman sells cow milk at the rate of Rs. 55 litre including a profit 12 per cent. He also sells buffalo milk at the rate of Rs. 36 per litre including a profit of 20%. How much profit will he earn in five days if he sells 8 litres of cow milk and 10 litres of buffalo milk per day?

$$\eqalign{ & {\text{Total}}\,{\text{cow}}\,{\text{milksold}}\,{\text{in}}\,{\text{five}}\,{\text{days}} \cr & = 5 \times 8 = 40\,{\text{litres}} \cr & {\text{Total}}\,{\text{buffalo}}\,{\text{milk}}\,{\text{sold}}\,{\text{in}}\,{\text{five}}\,{\text{days}} \cr & = 5 \times 10 = 50\,{\text{litres}} \cr & {\text{Hence}}, \cr & {\text{SP}}\,{\text{of}}\,{\text{40}}\,{\text{litres}}\,{\text{cow}}\,{\text{milk}} \cr & = 40 \times 55 = Rs.\,2200 \cr & {\text{Hence}}, \cr & {\text{Profit}}\,{\text{on}}\,{\text{cow}}\,{\text{milk}} \cr & = \frac{{ {2200 \times 12} }}{{112}} = Rs.\,235.71 \cr & {\text{Profit}}\,{\text{on}}\,{\text{buffalo}}\,{\text{milk}} \cr & = \frac{{ {50 \times 36 \times 20} }}{{120}} = Rs.\,300 \cr & {\text{Thus}}, \cr & {\text{Total}}\,{\text{Profit}} \cr & = 235.71 + 300 = Rs.\,535.71 \cr} $$