Tank U contained 4 times as many guppies as Tank V. When 30% of the guppies in Tank U and 30% of the guppies in Tank V were transferred to Tank W, Tank W had 90 guppies, which was 20% more guppies than before. How many more guppies were there in Tank W than Tank V in the end?

	Tank U	Tank V	Tank W
Before	4 u	1 u	5x1.5 = 7.5 u
Change	- 1.2 u	- 0.3 u	+ 1x1.5 = + 1.5 u
After	2.8 u	0.7 u	6x1.5 = 9 u

Number of guppies that were transferred from Tank U to Tank W
= 30% x 4 u
= ³⁰₁₀₀ x 4 u
= 1.2 u

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

20% = ²⁰₁₀₀ = ¹₅

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

Total number of guppies transferred from Tank U and Tank V into Tank W
= 1.2 u + 0.3 u
= 1.5 u

9 u = 90

1 u = 90 ÷ 9 = 10

Number of more guppies in Tank W than Tank V
= 9 u - 0.7 u
= 8.3 u
= 8.3 x 10
= 83

Answer(s): 83