Tank R contained 4 times as many guppies as Tank S. When 10% of the guppies in Tank R and 30% of the guppies in Tank S were transferred to Tank T, Tank T had 126 guppies, which was 20% more guppies than before. How many less guppies were there in Tank S than Tank R in the end?

	Tank R	Tank S	Tank T
Before	4 u	1 u	5x0.7 = 3.5 u
Change	- 0.4 u	- 0.3 u	+ 1x0.7 = + 0.7 u
After	3.6 u	0.7 u	6x0.7 = 4.2 u

Number of guppies that were transferred from Tank R to Tank T
= 10% x 4 u
= ¹⁰₁₀₀ x 4 u
= 0.4 u

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

20% = ²⁰₁₀₀ = ¹₅

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

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

4.2 u = 126

1 u = 126 ÷ 4.2 = 30

Number of less guppies in Tank S than Tank R
= 3.6 u - 0.7 u
= 2.9 u
= 2.9 x 30
= 87

Answer(s): 87