Tank J contained 3 times as many guppies as Tank K. When 20% of the guppies in Tank J and 30% of the guppies in Tank K were transferred to Tank L, Tank L had 180 guppies, which was 25% more guppies than before. How many less guppies were there in Tank K than Tank J in the end?

	Tank J	Tank K	Tank L
Before	3 u	1 u	4x0.9 = 3.6 u
Change	- 0.6 u	- 0.3 u	+ 1x0.9 = + 0.9 u
After	2.4 u	0.7 u	5x0.9 = 4.5 u

Number of guppies that were transferred from Tank J to Tank L
= 20% x 3 u
= ²⁰₁₀₀ x 3 u
= 0.6 u

Number of guppies that were transferred from Tank K to Tank L
= 30% x 1 u
= ³⁰₁₀₀ x 1 u
= 0.3 u

25% = ²⁵₁₀₀ = ¹₄

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

Total number of guppies transferred from Tank J and Tank K into Tank L
= 0.6 u + 0.3 u
= 0.9 u

4.5 u = 180

1 u = 180 ÷ 4.5 = 40

Number of less guppies in Tank K than Tank J
= 2.4 u - 0.7 u
= 1.7 u
= 1.7 x 40
= 68

Answer(s): 68