The museum tickets are priced at $9 and $6.  The number of $9-dollar tickets available is  1¹₃ that of the number of $6-dollar tickets. 3 out of 7 of the $9-dollar tickets and all the $6-dollar tickets were sold. The ticket sales amounted to $936. How much more would have been collected if all the tickets were sold?

	$9	$6
Comparing $9 and $6 tickets at first	4x7 = 28 u	3x7 = 21 u
Before	7x4 = 28 u
Change	- 3x4 = - 12 u	- 21 u
After	4x4 = 16 u	0 u

The number of 9 tickets at first is repeated.  Make the number of 9 tickets the same.  LCM of 7 and 4 is 28.

1¹₃ = ⁴₃

Number of $9 tickets : $6 tickets = 4 : 3

	$9	$6	Total
Number	12 u	21 u
Value	$9	$6
Total value	108 u	126 u	$936

Total amount collected from the sale of the sold tickets
= 108 u + 126 u
= 234 u

1 u = 936 ÷ 234 = 4

Number of $9-tickets left unsold
= 16 u 
= 16 x 4
= 64

More amount to be collected if all the tickets were sold
= 64 x 9
= $576

Answer(s): $576