Draw out the model to compare the cost between 1 table and one chair, which then tells you that cost of 1 table is equal to cost of 1 chair plus $270. It is given that $1200 was given to the cashier and $55 were returned, so the total cost of buying 1 table and 4 chairs will be $875. Since T=C+$270, so it can be substituted in to give 5 chairs + $270=$875 and you can use this to find the cost of a chair.