Tank S contained 3 times as many guppies as Tank T. When 20% of the guppies in Tank S and 30% of the guppies in Tank T were transferred to Tank U, Tank U had 45 guppies, which was 25% more guppies than before. How many less guppies were there in Tank T than Tank S in the end?

	Tank S	Tank T	Tank U
Before	3 u	1 u	4x0.9 = 3.6 u
Change	- 0.6 u	- 0.3 u	+ 1x0.9 = + 0.9 u
After	2.4 u	0.7 u	5x0.9 = 4.5 u

Number of guppies that were transferred from Tank S to Tank U
= 20% x 3 u
= ²⁰₁₀₀ x 3 u
= 0.6 u

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

25% = ²⁵₁₀₀ = ¹₄

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

Total number of guppies transferred from Tank S and Tank T into Tank U
= 0.6 u + 0.3 u
= 0.9 u

4.5 u = 45

1 u = 45 ÷ 4.5 = 10

Number of less guppies in Tank T than Tank S
= 2.4 u - 0.7 u
= 1.7 u
= 1.7 x 10
= 17

Answer(s): 17