Tank H contained 4 times as many guppies as Tank J. When 20% of the guppies in Tank H and 40% of the guppies in Tank J were transferred to Tank K, Tank K had 216 guppies, which was 20% 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	4 u	1 u	5x1.2 = 6 u
Change	- 0.8 u	- 0.4 u	+ 1x1.2 = + 1.2 u
After	3.2 u	0.6 u	6x1.2 = 7.2 u

Number of guppies that were transferred from Tank H to Tank K
= 20% x 4 u
= ²⁰₁₀₀ x 4 u
= 0.8 u

Number of guppies that were transferred from Tank J to Tank K
= 40% x 1 u
= ⁴⁰₁₀₀ x 1 u
= 0.4 u

20% = ²⁰₁₀₀ = ¹₅

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
= 0.8 u + 0.4 u
= 1.2 u

7.2 u = 216

1 u = 216 ÷ 7.2 = 30

Number of less guppies in Tank J than Tank H
= 3.2 u - 0.6 u
= 2.6 u
= 2.6 x 30
= 78

Answer(s): 78