Tank F contained 3 times as many guppies as Tank G. When 30% of the guppies in Tank F and 20% of the guppies in Tank G were transferred to Tank H, Tank H had 66 guppies, which was 20% more guppies than before. How many less guppies were there in Tank G than Tank F in the end?

	Tank F	Tank G	Tank H
Before	3 u	1 u	5x1.1 = 5.5 u
Change	- 0.9 u	- 0.2 u	+ 1x1.1 = + 1.1 u
After	2.1 u	0.8 u	6x1.1 = 6.6 u

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

Number of guppies that were transferred from Tank G to Tank H
= 20% x 1 u
= ²⁰₁₀₀ x 1 u
= 0.2 u

20% = ²⁰₁₀₀ = ¹₅

Some guppies from Tank F and Tank G were transferred to Tank H.  The total number of guppies transferred from Tank F and Tank G into Tank H is the same.

Total number of guppies transferred from Tank F and Tank G into Tank H
= 0.9 u + 0.2 u
= 1.1 u

6.6 u = 66

1 u = 66 ÷ 6.6 = 10

Number of less guppies in Tank G than Tank F
= 2.1 u - 0.8 u
= 1.3 u
= 1.3 x 10
= 13

Answer(s): 13