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

	Tank X	Tank Y	Tank Z
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 X to Tank Z
= 50% x 4 u
= ⁵⁰₁₀₀ x 4 u
= 2 u

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

20% = ²⁰₁₀₀ = ¹₅

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

Total number of guppies transferred from Tank X and Tank Y into Tank Z
= 2 u + 0.4 u
= 2.4 u

14.4 u = 288

1 u = 288 ÷ 14.4 = 20

Number of more guppies in Tank Z than Tank Y
= 14.4 u - 0.6 u
= 13.8 u
= 13.8 x 20
= 276

Answer(s): 276