Question

The lawton family spent a total of 26.75 on lunch. They bought 5 drinks and 3 sandwiches. Each drink costs $2.50 less than a sandwich. How do you find the cost of each sandwich?

Answer 1

The result makes no sense in the real world but according to the supplied values a sandwich costs `$4.90 58`
(Possibly the total bill should have been $`26.70` (???))

Explanation:

Let
`color(white)("XXX")d` represent the cost of a drink, and
`color(white)("XXX")s` represent the cost of a sandwich.

We are told
[1]`color(white)("XXX")5d+3s=26.75`
and
[1]`color(white)("XXX")d=s-2.50`

Using [2] we can replace `d` with `(s-2.50)` in [1] to get
`color(white)("XXX")5(s-2.50)+3s=26.75`

Simplifying
`color(white)("XXX")5s-12.50+3s=26.75`

`color(white)("XXX")8s= 39.25`

`color(white)("XXX")s=4.90 5/8`