Question

Seven pens and two pencils costs $6.59. seven pens and five cost $7.55. Find the cost of one pencil and the cost of one pen.

Answer 1

Let one pen be
`x` and one pencil as
`y`, we can produce two equations in terms of
`x` and
`y`


`7x+2y=6.59` ------> Equation 1

`7x+5y=7.55` ------> Equation 2

We can use either Elimination or Substitution method. Let's try the substitution method

Rearranging equation one to get
`7x=6.59-2y` and substitute into equation 2, gives

`(6.59-2y)+5y=7.55`

`6.59+3y=7.55`

`3y=7.55-6.59`

`3y=0.96`

`y=0.32`

We can use either equation one or equation to work out
`x`


`7x+2(0.32)=6.59`

`7x=6.59-0.64`

`x=0.85`

The price of one pen is $0.85
The price of one pencil is $0.32