Question

Lucy was given $28.87 to buy 3 story books and 4 comic books. However she bought 4 storybooks and 3 comic books and had $2.69 left. How much did each comic book cost?

Answer 1

$5.27 each

Explanation:

EQUATION 1:

--> Price of each story book: x

--> Quantity of story books: 3

--> Price of 3 story books: 3x

--> Price of each comic book: y

--> Quantity of comic books: 4

--> Price of 4 comic books: 4y

--> Total amount: $28.87

--> Equation----> 3x + 4y = 28.87

EQUATION 2:

--> Price of each story book: x

--> Quantity of story books: 4

--> Price of 3 story books: 4x

--> Price of each comic book: y

--> Quantity of comic books: 3

--> Price of 4 comic books: 3y

--> Total amount: $28.87 - 2.69 = $26.18

--> Equation----> 4x + 3y = 26.18

SOLVE:

3x + 4y = 28.87 (Multiply by 4)

4x + 3y = 26.18 (Multiply by -3)

--> 12x + 16y = 115.48

--> -12x - 9y = -78.54

12x-12x will be cancelled.

--> 16y-9y = 115.48-78.54

--> 7y = 36.94

--> y = 5.27

Therefore, each comic book cost $5.27.