Jeremy bought some notebooks at $4 each. He later sold them to his customers at $6 each. For customers who bought four notebooks were given another notebook for free. The customers bought either one or four notebooks. Jeremy gave away 140 free notebooks and collected a total of $580 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 5 notebooks each |
| Number |
1 u |
1 u - 700 |
700 |
| Value |
$4 |
$6 |
$6 |
| Total Value |
4 u |
6 u - $4200 |
$3360 |
Since 140 notebooks were given free, there were 140 customers who bought four notebooks each.
Number of notebooks that each customer would get if they bought four notebooks each and got 1 notebook free
= 4 + 1
= 5
Total number of notebooks for customers who each bought four notebooks
= 5 x 140
= 700
Number of notebooks for customers who each bought 1 notebook = 1 u - 700
Total amount collected from customers who bought 1 notebook each
= 6 x (1 u - 700)
= 6 u - 4200
Total amount collected from customers who bought four notebooks each
= 140 x 4 x 6
= $3360
Total amount collected from all the customers
= 6 u - 4200 + 3360
= 6 u - 840
Jeremy collected a total of $580 more than what he had paid for.
6 u - 840 = 4 u + 580
6 u - 4 u = 580 + 840
2 u = 1420
1 u = 1420 ÷ 2 = 710
Number of customers who bought just one notebook
= 1 u - 700
= 710 - 700
= 10
Answer(s): 10
