An apparel shop is running a special on t-shirts. The first shirt costs [tex]\$15[/tex], but each additional shirt is cheaper. The cost, [tex]c[/tex], for [tex]n[/tex] t-shirts is given by the equation [tex]c = 15 + 9(n - 1)[/tex].

1. How much will it cost to purchase 2 t-shirts?

2. How much will it cost to purchase 5 t-shirts?

3. How much does each additional t-shirt cost after the first one? How do you know?



Answer :

Sure! Let's go through these questions step by step.

### A. Cost to purchase 2 t-shirts

1. Identify the given formula:
The cost, [tex]\( c \)[/tex], for [tex]\( n \)[/tex] t-shirts is given by the equation:
[tex]\[ c = 15 + 9(n - 1) \][/tex]

2. Substitute [tex]\( n = 2 \)[/tex] into the formula:
[tex]\[ c = 15 + 9(2 - 1) \][/tex]

3. Simplify inside the parentheses first:
[tex]\[ c = 15 + 9(1) \][/tex]

4. Multiply:
[tex]\[ c = 15 + 9 \][/tex]

5. Add to find the total cost:
[tex]\[ c = 24 \][/tex]

So, the cost to purchase 2 t-shirts is [tex]\(\$ 24\)[/tex].

### B. Cost to purchase 5 t-shirts

1. Substitute [tex]\( n = 5 \)[/tex] into the formula:
[tex]\[ c = 15 + 9(5 - 1) \][/tex]

2. Simplify inside the parentheses:
[tex]\[ c = 15 + 9(4) \][/tex]

3. Multiply:
[tex]\[ c = 15 + 36 \][/tex]

4. Add to find the total cost:
[tex]\[ c = 51 \][/tex]

So, the cost to purchase 5 t-shirts is [tex]\(\$ 51\)[/tex].

### C. Cost of each additional t-shirt after the first one

To find how much each additional t-shirt costs after the first one, we examine the given formula:
[tex]\[ c = 15 + 9(n - 1) \][/tex]

In this formula:
- The first shirt costs [tex]\(\$ 15\)[/tex].
- The term [tex]\(\$ 9(n - 1)\)[/tex] accounts for the additional shirts.

Thus, for each additional t-shirt after the first one, the cost is:
[tex]\[ \$ 9 \][/tex]

We know this because [tex]\( 9 \)[/tex] is the coefficient of [tex]\((n-1)\)[/tex] in the given formula, representing the cost per additional t-shirt.

### Summary

- The cost to purchase 2 t-shirts is [tex]\(\$ 24\)[/tex].
- The cost to purchase 5 t-shirts is [tex]\(\$ 51\)[/tex].
- Each additional t-shirt after the first one costs [tex]\(\$ 9\)[/tex].