Final answer:
To write the system of equations for the given t-shirt companies, let x be the number of t-shirts. Ralph's total cost is CR = 7.50x + 10, and Frank's total cost is CF = 10x. The two equations together form the system.
Step-by-step explanation:
To write a system of equations for the scenario where Ralph's t-shirt company sells t-shirts for $7.50 each plus a flat rate of $10 for shipping, and Frank's t-shirt company sells t-shirts for $10 each with free shipping, let's use x to represent the number of t-shirts being sold. For Ralph's company, the total cost CR can be represented by the equation CR = 7.50x + 10. For Frank's company, the total cost CF can be represented by the equation CF = 10x. These two equations together form the system:
CR = 7.50x + 10
CF = 10x