The toy costs Rs. 27.00 and the three friends got back Rs. 3.00 and so the total comes to Rs. 30.00. They did not pay Rs. 2.00 to the servant and so it is not correct to add Rs. 2.00 to the actual cost of Rs. 27.00. It is here that the mistake lies. Out of Rs. 27.00, Rs. 25.00 went to the shop keeper and Rs. 2.00 to the servant.