SOLUTION: At a concession stand, five hotdogs and two hamburgers cost $10.25; two hotdogs and five hamburgers cost $12.50. How much does one hotdog cost? Thank you very much for your hel

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: At a concession stand, five hotdogs and two hamburgers cost $10.25; two hotdogs and five hamburgers cost $12.50. How much does one hotdog cost? Thank you very much for your hel      Log On


   



Question 734854: At a concession stand, five hotdogs and two hamburgers cost $10.25; two hotdogs and five hamburgers cost $12.50. How much does one hotdog cost?
Thank you very much for your help!

Found 2 solutions by MathLover1, rothauserc:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
let hotdogs be x and hamburgers y
if five hotdogs and two hamburgers cost $10.25, then
5x%2B2y=10.25.....eq.1
if two hotdogs and five hamburgers cost $12.50,then
2x%2B5y=12.50.....eq.2
now solve this system:

5x%2B2y=10.25.....eq.1
2x%2B5y=12.50.....eq.2
______________________________
5x%2B2y=10.25.....eq.1....solve for x
5x=10.25-2y
x=10.25%2F5-2y%2F5
x=2.05-0.4y......plug it in eq.2

2%282.05-0.4y%29%2B5y=12.50.....eq.2..solve for y

4.1-0.8y%2B5y=12.50
-0.8y%2B5y=12.50-4.1
4.2y=8.4
y=8.4%2F4.2
highlight%28y=2%29........hamburger cost
now find x
x=2.05-0.4%2A2
x=2.05-0.8
highlight%28x=1.25%29.....hotdog cost

check:
5x%2B2y=10.25.....eq.1
5%2A1.25%2B2%2A2=10.25
6.25%2B4=10.25
10.25=10.25

2x%2B5y=12.50.....eq.2
2%2A1.25%2B5%2A2=12.50
2.50%2B10=12.50
12.50=12.50

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = cost of hot dog, y = cost of hamburger,
we have
5x + 2y = 10.25 and
2x + 5y = 12.50
we need to know the value for x
solve the second equation for y and we have
y = (12.50 - 2x) / 5 = 2.50 - 2x/5
now we substitute for y in our first equation,
5x + 2 (2.50 - 2x/5) = 10.25 combining like terms,
5x + 5.00 - 4x/5 = 10.25 and
5x - 4x/5 = 5.25 and
25x - 4x = 26.25 and 21x = 26.25
x = $1.25, so the hot dog costs $1.25