I cannot figure out how to set up this problem. Half of the points are for reasoning and presentation of how to set up the problem and the other half is for the answer.
"You have an unlimited supply of 6-cent stamps and 11-cent stamps. You can make exact postage of 23 cents with two 6-cent stamps and one 11-cent stamp. However, you cannot make exact postage of 21 cents by using only 6-cent and 11-cent stamps. What is the greatest amount of exact postage you CANNOT make by using these stamps?"
I am not thinking about this problem right and could use any advice on how to begin to set it up. I keep thinking since I have an unlimited amount of the stamps then there can't be an answer... but I know that isn't right.
"You have an unlimited supply of 6-cent stamps and 11-cent stamps. You can make exact postage of 23 cents with two 6-cent stamps and one 11-cent stamp. However, you cannot make exact postage of 21 cents by using only 6-cent and 11-cent stamps. What is the greatest amount of exact postage you CANNOT make by using these stamps?"
I am not thinking about this problem right and could use any advice on how to begin to set it up. I keep thinking since I have an unlimited amount of the stamps then there can't be an answer... but I know that isn't right.