For delivery of a first class letter, the post office charges $0.25 for the first ounce and $0.20 for each additional ounce or fraction thereof.

A. If the input value is the number of ounces that the letter weighs and the output is the cost of mailing a letter is this relation a function? Explain.

B. If the input value is the cost of mailing the letter and the output is the weight of the letter, is this relation a function? Explain.

Please show your work, thank you!