$\"\"$

Let b be the initial set-up fee, t be the number of months, m be the charge per month and C be the total amount.

The total cost is $\"\"$ .

The number of months is $\"\"$ .

The charge per one month is 18 dollars.

The word $\"\"$ total cost C is the product of monthly cost m dollars and number of months t plus initial set-up fee b $\"\"$ represents the equation $\"\"$ . $\"\"$

To find the value of b, substitute the values of $\"\"$ in the equation $\"\"$ and solve for b.

$\"\"$

Subtract 36 from each side.

$\"\"$

$\"\"$ . $\"\"$

The initial set-up fee is 45 dollars.