A can of tennis balls costs $6. The total cost c of n cans, including sales tax t, is given by the equation c = 6n + t. Which is the best reason why c – t = 6n?
The reason why c = 6n + t is the same as c - t = 6n is because c is the sum of the addition problem. 6n and t are the addends. The inverse operation for addition is subtraction. c is the cost that will be reduced by t. The answer is still 6n.
