In a kiosk, some mini-helicopters and toy masks were on sale. ¹₅ of the items were mini-helicopters. ²₃ of the mini-helicopters and 168 toy masks were sold. There were ¹₆ of the items left in the kiosk. How many mini-helicopters and toy masks were there in the kiosk at first?

	Mini-helicopters	Toy masks	Total
Comparing mini-helicopters  and toy masks at first	1x6 = 6 u	4x6 = 24 u	5x6 = 30 u
Before	3x2 =  6 u		6x5 = 30 u
Change	- 2x2 = - 4 u	- 168	- 5x5 = - 25 u
After	1x2 = 2 u	3 u	1x5 = 5 u

 
The total number of toys at first is repeated.  Make the total number of toys at first the same. LCM of 5 and 6 is 30.

The number of mini-helicopters at first is repeated.  Make the number of mini-helicopters the same. LCM of 6 and 3 is 6. 

Number of toy masks left
= 5 u - 2 u
= 3 u

Number of toy masks sold
= 24 u - 3 u
= 21 u

21 u = 168

1 u = 168 ÷ 21 = 8

Number of mini-helicopters and toy masks at first
= 30 u
= 30 x 8
= 240

Answer(s): 240