Chapter 4.7, Problem 320E

In the following exercises, translate to a system of inequalities and solve.

320. Reiko needs to mail her Christmas cards and packages and wants to keep her mailing costs to no more than $500. The number of cards is at least 4 more than twice the number of packages. The cost of mailing a card (with pictures enclosed) is $3 and for a package the cost is $7.

(a) Write a system of inequalities to model this situation.

(b) Graph the system.

(c) Can she mail 60 cards and 26 packages?

(d) Can she mail 90 cards and 40 packages?