Question

At a bake sale, as student spent $11.00 buying 3 brownies and 5 cookies. His friend spent $3.95 buying 1 brownie and 2 cookies. What is the price of a brownie?

Answer 1

$
`$2.25`

Explanation:

Let
`b =` the cost of one brownie,
`c =` cost of one cookie

`3b + 5c = 11`

`b+2c = 3.95`

Times
`3` on both sides on the second equation above to get the following:

`3b + 6c = 11.85`

`3b+6c - (3b+5c) = 11.85-11`

`3b+6c-3b-5c = 0.85`

`c = 0.85`

To find the value of
`b`, use substitution:

`b+2c = 3.95`

`b = 3.95-2c`

`= 3.95 - 2*0.85`

`= 2.25`

`\therefore` the cost of a brownie is $
`$2.25`

Hope this helps :)