First, let's calculate the original price of the shirts:
The original price of one shirt is $18, so for three shirts:
\[ 3 \times 18 = 54 \text{ dollars} \]
Next, let's calculate the discount of 20% on the original price.
The discount amount can be calculated as:
\[ 0.20 \times 54 = 10.8 \text{ dollars} \]
Now, we subtract the discount from the original price to find the cost after the discount:
\[ 54 - 10.8 = 43.2 \text{ dollars} \]
Next, we need to calculate the 5% tax on the discounted price. We'll calculate this as follows:
\[ 0.05 \times 43.2 = 2.16 \text{ dollars} \]
Now, we can find Kayla's total bill by adding the tax to the discounted price:
\[ 43.2 + 2.16 = 45.36 \text{ dollars} \]
Now, we can complete the statements:
The cost of the shirts after the discount is $43.20.
A 5% tax adds an additional $2.16, so Kayla's total bill is $45.36.
Kayla does not have enough money to purchase all three shirts, as she only has $45.