The cost of purchasing shirts can be represented mathematically. If "x" represents the number of shirts bought, the total cost "C" can be described by the following linear equation:

$C = 9x + 22$

• 9x: Represents the cost for each shirt (9 dollars per shirt times the number of shirts).
• 22: Represents the one-time design fee.

So, the total cost depends on the number of shirts purchased.

Do you want to solve this for a specific number of shirts? Or would you like more details on how the formula works?

Here are 5 related questions:

1. How many shirts does he plan to buy?
2. What would the total cost be for 5 shirts?
3. How does the cost change if the design fee increases?
4. What if the price per shirt decreases to $7—how would the equation change?
5. How does this relate to real-world applications of linear equations?

Tip: Linear equations like this are helpful in budgeting, especially when there is a fixed cost plus a variable cost (like in this case).