The concert hall tickets are priced at $18 and $15.  The number of $18-dollar tickets available is  2⁵₆ that of the number of $15-dollar tickets. 3 out of 7 of the $18-dollar tickets and all the $15-dollar tickets were sold. The ticket sales amounted to $18576. How much more would have been collected if all the tickets were sold?

	$18	$15
Comparing $18 and $15 tickets at first	17x7 = 119 u	6x7 = 42 u
Before	7x17 = 119 u
Change	- 3x17 = - 51 u	- 42 u
After	4x17 = 68 u	0 u

The number of 18 tickets at first is repeated.  Make the number of 18 tickets the same.  LCM of 7 and 17 is 119.

2⁵₆ = ¹⁷₆

Number of $18 tickets : $15 tickets = 17 : 6

	$18	$15	Total
Number	51 u	42 u
Value	$18	$15
Total value	918 u	630 u	$18576

Total amount collected from the sale of the sold tickets
= 918 u + 630 u
= 1548 u

1 u = 18576 ÷ 1548 = 12

Number of $18-tickets left unsold
= 68 u 
= 68 x 12
= 816

More amount to be collected if all the tickets were sold
= 816 x 18
= $14688

Answer(s): $14688