The museum tickets are priced at $13 and $6.  The number of $13-dollar tickets available is  2¹₄ that of the number of $6-dollar tickets. 2 out of 3 of the $13-dollar tickets and all the $6-dollar tickets were sold. The ticket sales amounted to $204. How much more would have been collected if all the tickets were sold?

	$13	$6
Comparing $13 and $6 tickets at first	9x1 = 9 u	4x1 = 4 u
Before	3x3 = 9 u
Change	- 2x3 = - 6 u	- 4 u
After	1x3 = 3 u	0 u

The number of 13 tickets at first is repeated.  Make the number of 13 tickets the same.  LCM of 3 and 9 is 9.

2¹₄ = ⁹₄

Number of $13 tickets : $6 tickets = 9 : 4

	$13	$6	Total
Number	6 u	4 u
Value	$13	$6
Total value	78 u	24 u	$204

Total amount collected from the sale of the sold tickets
= 78 u + 24 u
= 102 u

1 u = 204 ÷ 102 = 2

Number of $13-tickets left unsold
= 3 u 
= 3 x 2
= 6

More amount to be collected if all the tickets were sold
= 6 x 13
= $78

Answer(s): $78