A student bought a box of calculators for $300. She gave 15 of them to the teacher and then sold the rest for $330, making a profit of $1.50 on each one. How many calculators were in the box at the start? What was the original price of each calculator?

Given :

A student bought a box of calculators for $300. She gave 15 of them to the teacher and then sold the rest for $330, making a profit of $1.50 on each one.

To Find :

How many calculators were in the box at the start? What was the original price of each calculator?

Solution :

Let, initial number of calculators are x and price of each calculator is p.

So, overall profit is equal to profit on each multiplied by remaining calculator.

( x - 15)( 1.50 ) = 330 - 300

x - 15 = 20

x = 35

Also, original price of each calculator is :

p = $300/35

p = $8.57

Hence, this is the required solution.