SOLUTION: David bought 3 hamburgers and 2 servings of french fries at Diane's Drive -Up for $6.25. If a serving of fries costs .25 cents more then a hamburger, what is the cost of each?

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: David bought 3 hamburgers and 2 servings of french fries at Diane's Drive -Up for $6.25. If a serving of fries costs .25 cents more then a hamburger, what is the cost of each?       Log On


   

Question 188292: David bought 3 hamburgers and 2 servings of french fries at Diane's Drive -Up for $6.25. If a serving of fries costs .25 cents more then a hamburger, what is the cost of each?



answer: The hamburgers at Diane's cost $ 1.15 ;the fries cost $1.40.

need a full break down of how my text book got hamburgers $1.15 and fries $1.40 as an answer
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
David bought 3 hamburgers and 2 servings of french fries at Diane's Drive -Up for $6.25.
If a serving of fries costs .25 cents more then a hamburger, what is the cost of each?
:
Let h = cost of a hamburger
Let f = cost of an order of fries
:
Write an equation for each statement
"David bought 3 hamburgers and 2 servings of french fries at Diane's Drive -Up for $6.25."
3h + 2f = 6.25
:
"If a serving of fries costs .25 cents more then a hamburger,"
f = h + .25
:
what is the cost of each?
:
we know; 3h + 2f = 6.25
Substitute (h+.25) for f in this equation:
3h + 2(h+.25) = 6.25
3h + 2h + .50 = 6.25
5h = 6.25 - .50
5h = 5.75
h = 5.75%2F5
h = $1.15 for a hamburger
:
Find f using the 1st equation; f = h + .25
f = 1.15 + .25
f = $1.40 for fries
;
:
you can prove it to yourself: 3h + 2f = 6.25, therefore:
3(1.15) + 2(1.40) =
3.45 + 2.80 = 6.25