Case-Study 2: Read the following passage and answer the questions given below

Three friends Ravi, Raju and Rohit were doing buying and selling of stationery items in a market. The price of per dozens of pens, notebooks and toys are Rupees x, y and z respectively. Ravi purchases 4 dozen of notebooks and sells 2 dozen of pens 5 dozen of toys. Raju purchases 2 dozen of toy and sells 3 dozen of pens and 1 dozen of notebooks. Rohit purchases one dozen of pens and sells 3 dozen of notebooks and one dozen of toys.

In the process, Ravi, Raju and Rohit earn Rs. 1500, Rs. 100 and Rs. 400 respectively.