Question

john order 3 burgers and 2 fries for $12.15. Emily bought 4 burgers and 3 fries for $16.80. How much did the pay for each burger and order of fries?

Answer 1

Cost of burger = $2.85 and Cost of fries = $ 1.80.

Explanation:

Given : john order 3 burgers and 2 fries for $12.15. Emily bought 4 burgers and 3 fries for $16.80.

To find : How much did the pay for each burger and order of fries.

Solution : We have given 3 burgers and 2 fries for $12.15.

Let the cost of 1 burger = x .

Let the cost of 1 Fries = y .

3 x + 2 y = $12.15 ------(1)

4 x + 3 y = $16.80-----(2)

On multiplying (i) by 4 and (ii) by 3 and subtracting the equation .

12x + 8y = $48 .60

(-)12x +(-) 9y = (-)$50 .40

_____________

0 -y = -$ 1.80

y = $ 1.80.

3x + 2(1.80) = $12.15 .

3x + 3.60 = 12.15

3x = 12.15 - 3.60

3x = 8.55

On dividing both sides by 3.

x = $2 .85

Therefore, Cost of burger = $2.85 and Cost of fries = $ 1.80.

Answer 2

They paid $2.85 for each burger and $1.8 for each order of fries

Explanation:

It will be solved simultaneously,

let x represent burger and y represent fries

John's order gives the first equation

3x + 2y = 12.15 ........(1)

Emily's order gives the second equation

4x + 3y = 16.80 ..........(2)

multiply equation (1) by 3 and equation (2) by 2 so as to eliminate y

9x + 6y = 36.45 ....... (3)

8x + 6y = 33.6 ........... (4)

subtract equation (4) from (3)

9x - 8x + 6y -6y = 36.45 - 33.6

x = 2.85

substitute x= 2.85 in equation (1)

3(2.85) + 2y = 12. 15

8.55 + 2y = 12.15

2y = 12.15 -8.55

2y = 3.6

y = 1.8