Question

At burger world, fries cost 2.50 each and hamburgers cost 4.75 each. Andrea and her friends ordered 19 items, all burgers and fries for a total of 65.50 before tax. How many of each item did they purchase

Answer 1

Andrea and her friends bought 11 fries and 8 hamburgers

Solution:

Let "f" be the number of fries bought

Let "h" be the number of hamburgers bought

Cost of 1 fries = $ 2.50

Cost of 1 hamburger = $ 4.75

Given that Andrea and her friends ordered 19 items

number of fries bought + number of hamburgers bought = 19

f + h = 19 ---- eqn 1

They ordered for total of 65.50

number of fries bought x Cost of 1 fries + number of hamburgers bought x Cost of 1 hamburger = 65.50

`f * 2.50 + h * 4.75 = 65.50`

2.5f + 4.75h = 65.5 --- eqn 2

Let us solve eqn 1 and eqn 2

From eqn 1,

f = 19 - h ----- eqn 3

Substitute eqn 3 in eqn 2

2.5(19 - h) + 4.75h = 65.5

47.5 - 2.5h + 4.75h = 65.5

h = 65.5 - 47.5

2.25h = 18

h = 8

Substitute h = 8 in eqn 3

f = 19 - 8 = 11

f = 11

Thus they bought 11 fries and 8 hamburgers