Tank X contained 4 times as many guppies as Tank Y. When 30% of the guppies in Tank X and 10% of the guppies in Tank Y were transferred to Tank Z, Tank Z had 130 guppies, which was 25% more guppies than before. How many less guppies were there in Tank Y than Tank X in the end?

	Tank X	Tank Y	Tank Z
Before	4 u	1 u	4x1.3 = 5.2 u
Change	- 1.2 u	- 0.1 u	+ 1x1.3 = + 1.3 u
After	2.8 u	0.9 u	5x1.3 = 6.5 u

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

Number of guppies that were transferred from Tank Y to Tank Z
= 10% x 1 u
= ¹⁰₁₀₀ x 1 u
= 0.1 u

25% = ²⁵₁₀₀ = ¹₄

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
= 1.2 u + 0.1 u
= 1.3 u

6.5 u = 130

1 u = 130 ÷ 6.5 = 20

Number of less guppies in Tank Y than Tank X
= 2.8 u - 0.9 u
= 1.9 u
= 1.9 x 20
= 38

Answer(s): 38