9. Greg needs at least $1.60 in stamps to mail a package. He has 284 and 4¢ stamps. He can use no more than twenty 4¢ stamps as he only has one book left.
a) Write a system of linear inequalities to represent
this situation, then graph.
b) Using your graph, give two possible combinations
of stamps that Greg can use to ensure he mails
his package with the correct postage.