Question

A store sells packages of comic books with a poster. A poster and 2 comics cost ​$7.99. A poster and 11 comics cost ​$16.99. Write a linear function rule that models the cost y of a package containing any number x of comic books.

Answer 1

Answer:

$y=x+5.99$

Step-by-step explanation:

A poster and 2 comics cost ​$7.99

(2,7.99)

A poster and 11 comics cost ​$16.99.

(11,16.99)

Let y be the cost of package and x be the no. of comics

We will use two point slope form :

$(x_1,y_1)=(2,7.99)$

$(x_2,y_2)=(11,16.99)$

Formula : $y-y_1=\frac{y_2-y_1}{x_2-x_1}(x-x_1)$

Substitute the values:

$y-y_1=\frac{y_2-y_1}{x_2-x_1}(x-x_1)$

$y-7.99=\frac{16.99-7.99}{11-2}(x-2)$

$y-7.99=1(x-2)$

$y-7.99=x-2$

$y=x-2+7.99$

$y=x+5.99$

Hence a linear function rule that models the cost y of a package containing any number x of comic books is $y=x+5.99$