The diagrams show the rates of diamond and emerald in a range of sizes. Both graphs are straight lines through the origin: for diamond the price rises to 5 Lakh Rs/carat at a weight of 2.5 carat, and for emerald it rises to 2.5 Lakh Rs/carat at the same weight. A person wants to buy a diamond and an emerald of identical size for a total of Rs. 6,75,000/-. What is that size?