Tank W contained 4 times as many guppies as Tank X. When 20% of the guppies in Tank W and 20% of the guppies in Tank X were transferred to Tank Y, Tank Y had 240 guppies, which was 20% more guppies than before. How many less guppies were there in Tank X than Tank W in the end?

	Tank W	Tank X	Tank Y
Before	4 u	1 u	5x1 = 5 u
Change	- 0.8 u	- 0.2 u	+ 1x1 = + 1 u
After	3.2 u	0.8 u	6x1 = 6 u

Number of guppies that were transferred from Tank W to Tank Y
= 20% x 4 u
= ²⁰₁₀₀ x 4 u
= 0.8 u

Number of guppies that were transferred from Tank X to Tank Y
= 20% x 1 u
= ²⁰₁₀₀ x 1 u
= 0.2 u

20% = ²⁰₁₀₀ = ¹₅

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

Total number of guppies transferred from Tank W and Tank X into Tank Y
= 0.8 u + 0.2 u
= 1 u

6 u = 240

1 u = 240 ÷ 6 = 40

Number of less guppies in Tank X than Tank W
= 3.2 u - 0.8 u
= 2.4 u
= 2.4 x 40
= 96

Answer(s): 96