To mail a letter to Vienna, Austria the post office charges a flat rate of nine dollars and an additional $.50 for every ounce the letter weighs. The cost of mailing a letter is determined by the equation Y equals 0.50x+9.00 where y is the cost of the postage and X is the weight of the letter in ounces. Use the graph to estimate to the nearest quarter of a dollar (0.25) The cost to send a letter that weighs 6 ounces.