In a shop, some water guns and rubik's cubes were on sale. ¹₅ of the items were water guns. ²₃ of the water guns and 42 rubik's cubes were sold. There were ¹₆ of the items left in the shop. How many water guns and rubik's cubes were there in the shop at first?

	Water guns	Rubik's cubes	Total
Comparing water guns  and rubik's cubes at first	1x6 = 6 u	4x6 = 24 u	5x6 = 30 u
Before	3x2 =  6 u		6x5 = 30 u
Change	- 2x2 = - 4 u	- 42	- 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 water guns at first is repeated.  Make the number of water guns the same. LCM of 6 and 3 is 6. 

Number of rubik's cubes left
= 5 u - 2 u
= 3 u

Number of rubik's cubes sold
= 24 u - 3 u
= 21 u

21 u = 42

1 u = 42 ÷ 21 = 2

Number of water guns and rubik's cubes at first
= 30 u
= 30 x 2
= 60

Answer(s): 60