Wesley bought some pencils at $2 each. He later sold them to his customers at $7 each. For customers who bought two pencils were given another pencil for free. The customers bought either one or two pencils. Wesley gave away 200 free pencils and collected a total of $1750 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 3 pencils each
Number	1 u	1 u - 600	600
Value	$2	$7	$7
Total Value	2 u	7 u - $4200	$2800

Since 200 pencils were given free, there were 200 customers who bought two pencils each.

Number of pencils that each customer would get if they bought two pencils each and got 1 pencil free
= 2 + 1
= 3

Total number of pencils for customers who each bought two pencils 
= 3 x 200
= 600

Number of pencils for customers who each bought 1 pencil = 1 u - 600

Total amount collected from customers who bought 1 pencil each
= 7 x (1 u - 600)
= 7 u - 4200

Total amount collected from customers who bought two pencils each
= 200 x 2 x 7
= $2800

Total amount collected from all the customers
= 7 u - 4200 + 2800
= 7 u - 1400

Wesley collected a total of $1750 more than what he had paid for.

7 u - 1400 = 2 u + 1750
7 u - 2 u = 1750 + 1400
5 u = 3150

1 u = 3150 ÷ 5 = 630

Number of customers who bought just one pencil
= 1 u - 600
= 630 - 600
= 30

Answer(s): 30