Tank X contained 3 times as many guppies as Tank Y. When 30% of the guppies in Tank X and 30% of the guppies in Tank Y were transferred to Tank Z, Tank Z had 144 guppies, which was 50% 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	3 u	1 u	2x1.2 = 2.4 u
Change	- 0.9 u	- 0.3 u	+ 1x1.2 = + 1.2 u
After	2.1 u	0.7 u	3x1.2 = 3.6 u

Number of guppies that were transferred from Tank X to Tank Z
= 30% x 3 u
= ³⁰₁₀₀ x 3 u
= 0.9 u

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

50% = ⁵⁰₁₀₀ = ¹₂

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
= 0.9 u + 0.3 u
= 1.2 u

3.6 u = 144

1 u = 144 ÷ 3.6 = 40

Number of less guppies in Tank Y than Tank X
= 2.1 u - 0.7 u
= 1.4 u
= 1.4 x 40
= 56

Answer(s): 56