Question

At an airport restaurant, two sodas and four hamburgers cost $12.00. An order of four sodas and two hamburgers costs $9.00. How much does one hamburger cost?

Answer 1

let cost of soda be x

and cost of hamburger be y

By first condition

2x+4y=12

and by second condition

4x+2y=9

Add both equations

2x+4y=12

+

4x+2y=9

______________

6x+6y=21

2x+2y=7

subtract two from one

-2x+2y=-3

2x-2y=3

add 3 and 4

4x=10

x=10/4

x=$2.5

y=$1