In a mall, some rubber duckies and mini-helicopters were on sale. ¹₁₁ of the items were rubber duckies. ²₃ of the rubber duckies and 452 mini-helicopters were sold. There were ¹₁₂ of the items left in the mall. How many rubber duckies and mini-helicopters were there in the mall at first?

	Rubber duckies	Mini-helicopters	Total
Comparing rubber duckies  and mini-helicopters at first	1x12 = 12 u	10x12 = 120 u	11x12 = 132 u
Before	3x4 =  12 u		12x11 = 132 u
Change	- 2x4 = - 8 u	- 452	- 11x11 = - 121 u
After	1x4 = 4 u	7 u	1x11 = 11 u

 
The total number of toys at first is repeated.  Make the total number of toys at first the same. LCM of 11 and 12 is 132.

The number of rubber duckies at first is repeated.  Make the number of rubber duckies the same. LCM of 12 and 3 is 12. 

Number of mini-helicopters left
= 11 u - 4 u
= 7 u

Number of mini-helicopters sold
= 120 u - 7 u
= 113 u

113 u = 452

1 u = 452 ÷ 113 = 4

Number of rubber duckies and mini-helicopters at first
= 132 u
= 132 x 4
= 528

Answer(s): 528