Question

The bookstore bought two books for $45, with a profit of 40%. Find the cost of each book if the first book's profit was 25% and the second one's profit was 50%.

Answer 1

Cost of first book is $18

Cost of second book is $27

Explanation:

Given : The bookstore bought two books for $45, with a profit of 40%. If the first book's profit was 25% and the second one's profit was 50%.

To find : The cost of each book.

Solution :

Let x be the cost of first book.

Let y be the cost of second book.

The bookstore bought two books for $45

i.e,
`x+y=45` .......[1]

The first book's profit was 25%

i.e, 25% of x is
`(25)/(100)* x=0.25x`

The second one's profit was 50%.

i.e, 50% of y is
`(50)/(100)* x=0.50y`

Book bought at $45 with profit 40%

`(40)/(100)* 45=18`

i.e,
`0.25x+0.50y=18` .......[2]

Solving equation [1] and [2]

Substitute x=45-y from [1] in [2]

`0.25x+0.50y=18`

`0.25(45-y)+0.50y=18`

`11.25-0.25y+0.50y=18`

`0.25y=6.75`

`y=27`

Put back in [1]

`x+27=45`

`x=18`

Therefore, Cost of first book is $18

Cost of second book is $27