Tank H contained 3 times as many guppies as Tank J. When 30% of the guppies in Tank H and 10% of the guppies in Tank J were transferred to Tank K, Tank K had 90 guppies, which was 50% more guppies than before. How many less guppies were there in Tank J than Tank H in the end?

	Tank H	Tank J	Tank K
Before	3 u	1 u	2x1 = 2 u
Change	- 0.9 u	- 0.1 u	+ 1x1 = + 1 u
After	2.1 u	0.9 u	3x1 = 3 u

Number of guppies that were transferred from Tank H to Tank K
= 30% x 3 u
= ³⁰₁₀₀ x 3 u
= 0.9 u

Number of guppies that were transferred from Tank J to Tank K
= 10% x 1 u
= ¹⁰₁₀₀ x 1 u
= 0.1 u

50% = ⁵⁰₁₀₀ = ¹₂

Some guppies from Tank H and Tank J were transferred to Tank K.  The total number of guppies transferred from Tank H and Tank J into Tank K is the same.

Total number of guppies transferred from Tank H and Tank J into Tank K
= 0.9 u + 0.1 u
= 1 u

3 u = 90

1 u = 90 ÷ 3 = 30

Number of less guppies in Tank J than Tank H
= 2.1 u - 0.9 u
= 1.2 u
= 1.2 x 30
= 36

Answer(s): 36