Question

Can someone please help me with this problem asap? Thanks!! :))

Answer 1

Answer:
`\$4.34`

Explanation:

We have the following information:

Fredburguer
`F`, milkshake
`M` and an order of fries
`f` costs
`\$3.72`:

`F+M+f=\$3.72` (1)

One Fredburguer is equal to a milkshake plus orders of fries:

`F=M+2f` (2)

Three milshakes is equal to a Fredburguer plus an order of fries:

`3M=F+f` (3)

And we are asked: If we have a Fredburguer, a milkshake and two orders of fries, how much do we have to pay?

`F+M+2f=x` (4)

Well with the first three equations we have a system of equations to solve. Let's begin by isolating
`F` from (3):

`F=3M-f` (5)

Making (2)=(5):

`M+2f=3M-f` (6)

Isolating
`f`:

`f=(2)/(3)M` (7)

Substituting (7) in (2):

`F=M+2((2)/(3)M)` (8)

Isolating
`F`:

`F=(7)/(3)M` (9)

Substituting (7) and (9) in (1):

`(7)/(3)M+M+(2)/(3)M=\$3.72` (10)

Isolating
`M`:

`M=\$0.93` (11) This is the cost of a Milkshake

Substituting (11) in (7):

`f=(2)/(3)\$0.93` (12)

`f=\$0.62` (13) This is the cost of an order of frieds

Substituting (11) in (9):

`F=(7)/(3)\$0.93` (14)

`F=\$2.17` (15) This is the cost of a Fredburguer

Substituting (11), (13) and (15) in (4):

`\$2.17+\$0.93+2(\$0.62)=x` (16)

Finally:

`x=\$4.34` This is the cost of a Fredburguer, a milkshake and two orders of fries