Tank K contained 2 times as many guppies as Tank L. When 40% of the guppies in Tank K and 10% of the guppies in Tank L were transferred to Tank M, Tank M had 180 guppies, which was 25% more guppies than before. How many more guppies were there in Tank M than Tank L in the end?

	Tank K	Tank L	Tank M
Before	2 u	1 u	4x0.9 = 3.6 u
Change	- 0.8 u	- 0.1 u	+ 1x0.9 = + 0.9 u
After	1.2 u	0.9 u	5x0.9 = 4.5 u

Number of guppies that were transferred from Tank K to Tank M
= 40% x 2 u
= ⁴⁰₁₀₀ x 2 u
= 0.8 u

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

25% = ²⁵₁₀₀ = ¹₄

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

Total number of guppies transferred from Tank K and Tank L into Tank M
= 0.8 u + 0.1 u
= 0.9 u

4.5 u = 180

1 u = 180 ÷ 4.5 = 40

Number of more guppies in Tank M than Tank L
= 4.5 u - 0.9 u
= 3.6 u
= 3.6 x 40
= 144

Answer(s): 144