John bought some pencils at $6 each. He later sold them to his customers at $10 each. For customers who bought three pencils were given another pencil for free. The customers bought either one or three pencils. John gave away 180 free pencils and collected a total of $1200 more than what he had paid for. How many customers bought just one pencil each?
|
Pencils sold |
Pencils given to customers who got 1 pencil each |
Pencils given to customers who got 4 pencils each |
Number |
1 u |
1 u - 720 |
720 |
Value |
$6 |
$10 |
$10 |
Total Value |
6 u |
10 u - $7200 |
$5400 |
Since 180 pencils were given free, there were 180 customers who bought three pencils each.
Number of pencils that each customer would get if they bought three pencils each and got 1 pencil free
= 3 + 1
= 4
Total number of pencils for customers who each bought three pencils
= 4 x 180
= 720
Number of pencils for customers who each bought 1 pencil = 1 u - 720
Total amount collected from customers who bought 1 pencil each
= 10 x (1 u - 720)
= 10 u - 7200
Total amount collected from customers who bought three pencils each
= 180 x 3 x 10
= $5400
Total amount collected from all the customers
= 10 u - 7200 + 5400
= 10 u - 1800
John collected a total of $1200 more than what he had paid for.
10 u - 1800 = 6 u + 1200
10 u - 6 u = 1200 + 1800
4 u = 3000
1 u = 3000 ÷ 4 = 750
Number of customers who bought just one pencil
= 1 u - 720
= 750 - 720
= 30
Answer(s): 30