Tank Q contained 3 times as many guppies as Tank R. When 10% of the guppies in Tank Q and 40% of the guppies in Tank R were transferred to Tank S, Tank S had 168 guppies, which was 20% more guppies than before. How many more guppies were there in Tank S than Tank R in the end?

	Tank Q	Tank R	Tank S
Before	3 u	1 u	5x0.7 = 3.5 u
Change	- 0.3 u	- 0.4 u	+ 1x0.7 = + 0.7 u
After	2.7 u	0.6 u	6x0.7 = 4.2 u

Number of guppies that were transferred from Tank Q to Tank S
= 10% x 3 u
= ¹⁰₁₀₀ x 3 u
= 0.3 u

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

20% = ²⁰₁₀₀ = ¹₅

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

Total number of guppies transferred from Tank Q and Tank R into Tank S
= 0.3 u + 0.4 u
= 0.7 u

4.2 u = 168

1 u = 168 ÷ 4.2 = 40

Number of more guppies in Tank S than Tank R
= 4.2 u - 0.6 u
= 3.6 u
= 3.6 x 40
= 144

Answer(s): 144