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.