Tank V contained 3 times as many guppies as Tank W. When 10% of the guppies in Tank V and 30% of the guppies in Tank W were transferred to Tank X, Tank X had 120 guppies, which was 25% more guppies than before. How many less guppies were there in Tank W than Tank V in the end?

	Tank V	Tank W	Tank X
Before	3 u	1 u	4x0.6 = 2.4 u
Change	- 0.3 u	- 0.3 u	+ 1x0.6 = + 0.6 u
After	2.7 u	0.7 u	5x0.6 = 3 u

Number of guppies that were transferred from Tank V to Tank X
= 10% x 3 u
= ¹⁰₁₀₀ x 3 u
= 0.3 u

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

25% = ²⁵₁₀₀ = ¹₄

Some guppies from Tank V and Tank W were transferred to Tank X.  The total number of guppies transferred from Tank V and Tank W into Tank X is the same.

Total number of guppies transferred from Tank V and Tank W into Tank X
= 0.3 u + 0.3 u
= 0.6 u

3 u = 120

1 u = 120 ÷ 3 = 40

Number of less guppies in Tank W than Tank V
= 2.7 u - 0.7 u
= 2 u
= 2 x 40
= 80

Answer(s): 80