The museum tickets are priced at $18 and $12.  The number of $18-dollar tickets available is  2¹₆ that of the number of $12-dollar tickets. 2 out of 3 of the $18-dollar tickets and all the $12-dollar tickets were sold. The ticket sales amounted to $7524. How much more would have been collected if all the tickets were sold?

	$18	$12
Comparing $18 and $12 tickets at first	13x3 = 39 u	6x3 = 18 u
Before	3x13 = 39 u
Change	- 2x13 = - 26 u	- 18 u
After	1x13 = 13 u	0 u

The number of 18 tickets at first is repeated.  Make the number of 18 tickets the same.  LCM of 3 and 13 is 39.

2¹₆ = ¹³₆

Number of $18 tickets : $12 tickets = 13 : 6

	$18	$12	Total
Number	26 u	18 u
Value	$18	$12
Total value	468 u	216 u	$7524

Total amount collected from the sale of the sold tickets
= 468 u + 216 u
= 684 u

1 u = 7524 ÷ 684 = 11

Number of $18-tickets left unsold
= 13 u 
= 13 x 11
= 143

More amount to be collected if all the tickets were sold
= 143 x 18
= $2574

Answer(s): $2574