5b + 9s = 28.75
10b + 10s = 47.5
Multiply all terms in equation #1 by 2.
10b + 18s = 57.5
Subtract both equations from each-other.
8s = 10
Divide both sides by 8.
s = 1.25
The cost of a soda is 1.25, and because we know this, we can plug it into either equation to solve for the cost of b, a burger.
5b + 9(1.25) = 28.75
5b + 11.25 = 28.75
Subtract 11.25 from both sides.
5b = 17.5
Divide both sides by 5.
b = 3.5
The price of a soda is $1.25.
The price of a burger is $3.5.
