SOLUTION: Please help me with this question. Three burgers and four orders of fries total $16.80. Two burgers and six orders of fries total $17.20. How much does one burger cost? How much do

Question 90980: Please help me with this question. Three burgers and four orders of fries total $16.80. Two burgers and six orders of fries total $17.20. How much does one burger cost? How much does one order of fries cost?
Thank you
Answer by psbhowmick(878) (Show Source): You can put this solution on YOUR website!
Let cost of each burger = $x and cost of each fry = $y.
Then three burgers and four fries cost = $(3x + 4y).
This value is equal to $16.80.

3x + 4y = 16.80 ________(1)

Also, two burgers and six fries cost = $(2x + 6y).
This value is equal to $17.20.

2x + 6y = 17.20 ________(2)

Multiplying both sides of equation (1) by 2
6x + 8y = 33.60 ________(3)

Multiplying both sides of equation (2) by 3
6x + 18y = 51.60 ________(4)

Subtracting both sides of equation (3) from the respective sides of equation (4)
18y - 8y = 51.60 - 33.60
10y = 18
y = 18/10 = 1.80

Substituting this value of 'y' in equation (1) we have
3x + 4*1.80 = 16.80
3x + 7.20 = 16.80
3x = 16.80 - 7.20 = 9.60
x = 9.60/3 = 3.20

Thus, each burger costs $3.20 and each fry costs $1.80.
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