Question

2. On Friday, the Lee family had dinner at a

restaurant. They ordered 12 cheeseburgers and
4 chili bowls for $19.40. The following Friday,
the Lee family went back to the same restaurant.
They ordered 8 cheeseburgers and 6 chili bowls
for $16.60. How much does a cheeseburger
cost?

Answer 1

cheeseburger costs $1.25

Explanation:

let x be the cost of a cheeseburger and y the cost of chilli and set up 2 simultaneous equations, that is

12x + 4y = 19.4 → (1)

8x + 6y = 16.6 → (2)

multiplying (1) by 6 and (2) by - 4 and adding the result will eliminate y

72x + 24y = 116.4 → (3)

- 32x - 24y = - 66.4 → (4)

add (3) and (4) term by term to eliminate y

40x + 0 = 50

40x = 50 ( divide both sides by 40 )

x = 1.25

the cost of a cheeseburger is $1.25