Lee bought some notebooks at $6 each. He later sold them to his customers at $10 each. For customers who bought two notebooks were given another notebook for free. The customers bought either one or two notebooks. Lee gave away 130 free notebooks and collected a total of $340 more than what he had paid for. How many customers bought just one notebook each?
|
Notebooks sold |
Notebooks given to customers who got 1 notebook each |
Notebooks given to customers who got 3 notebooks each |
Number |
1 u |
1 u - 390 |
390 |
Value |
$6 |
$10 |
$10 |
Total Value |
6 u |
10 u - $3900 |
$2600 |
Since 130 notebooks were given free, there were 130 customers who bought two notebooks each.
Number of notebooks that each customer would get if they bought two notebooks each and got 1 notebook free
= 2 + 1
= 3
Total number of notebooks for customers who each bought two notebooks
= 3 x 130
= 390
Number of notebooks for customers who each bought 1 notebook = 1 u - 390
Total amount collected from customers who bought 1 notebook each
= 10 x (1 u - 390)
= 10 u - 3900
Total amount collected from customers who bought two notebooks each
= 130 x 2 x 10
= $2600
Total amount collected from all the customers
= 10 u - 3900 + 2600
= 10 u - 1300
Lee collected a total of $340 more than what he had paid for.
10 u - 1300 = 6 u + 340
10 u - 6 u = 340 + 1300
4 u = 1640
1 u = 1640 ÷ 4 = 410
Number of customers who bought just one notebook
= 1 u - 390
= 410 - 390
= 20
Answer(s): 20