Tank M contained 4 times as many guppies as Tank N. When 50% of the guppies in Tank M and 40% of the guppies in Tank N were transferred to Tank P, Tank P had 288 guppies, which was 20% more guppies than before. How many less guppies were there in Tank N than Tank M in the end?

	Tank M	Tank N	Tank P
Before	4 u	1 u	5x2.4 = 12 u
Change	- 2 u	- 0.4 u	+ 1x2.4 = + 2.4 u
After	2 u	0.6 u	6x2.4 = 14.4 u

Number of guppies that were transferred from Tank M to Tank P
= 50% x 4 u
= ⁵⁰₁₀₀ x 4 u
= 2 u

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

20% = ²⁰₁₀₀ = ¹₅

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

Total number of guppies transferred from Tank M and Tank N into Tank P
= 2 u + 0.4 u
= 2.4 u

14.4 u = 288

1 u = 288 ÷ 14.4 = 20

Number of less guppies in Tank N than Tank M
= 2 u - 0.6 u
= 1.4 u
= 1.4 x 20
= 28

Answer(s): 28