Question

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. What is the cost of the most expensive book I can buy with my money and the coupon? (Assume that there are books of every possible price in the bookstore. It's a large bookstore!)

Answer 1

The cost of the most expensive book which he can buy with his money is less than or equal to 43.5

Explanation:

Given : I'm at a bookstore with $35 in my pocket and a 20%-off coupon.

To Find: . What is the cost of the most expensive book I can buy with my money and the coupon?

Solution :

let the cost of most expensive book be x

Since there is 20 % of on every book

So, After 20 % off on the most expensive

The cost will be : x - (x of 20%)

`=x-(20)/(100) x`

`=(80)/(100) x`

`=(4)/(5) x`

Since we are given that he has only $35 so he cannot pay more than 35

so, equation becomes :

`(4)/(5) x\leq 35`

`x\leq(5*35)/(4)`

`x\leq(175)/(4)`

`x\leq43.5`

So , the cost of the most expensive book which he can buy with his money is less than or equal to 43.5

Answer 2

$43.75

Explanation:

Let x represent the cost of the book. We have a 20% off coupon; this means we will pay 100-20 = 80% of the cost.

80% = 80/100 = 0.8; this means we the cost we pay will be represented using the expression 0.8x.

Since we only have $35, this gives us the equation

0.8x = 35

Divide both sides by 0.8:

0.8x/0.8 = 35/0.8

x = $43.75