invoice clerk receives bill ksh3750 10 blank ledger books and 3 filing trays after discovery

An invoice clerk receives a bill of Ksh.3750 for 10 blank ledger books and 3 filing trays. After discovery that the order had been written out incorrectly, the clerk and the supplier agree that the clerk returns 3 of the ledger books. The supplier sends an extra filing tray. Given that there will be an extra Ksh.250 to pay and there is a 10% discount for orders of 10 ledger books or more, you are required: (i) Derive linear equations in X and Y to represent the component of the original and revised invoices, where x is the price of the single ledger book and y is the price of a filing tray. (ii) Solve the equations for x and y