Tank C contained 3 times as many guppies as Tank D. When 50% of the guppies in Tank C and 20% of the guppies in Tank D were transferred to Tank E, Tank E had 408 guppies, which was 20% more guppies than before. How many more guppies were there in Tank E than Tank D in the end?

	Tank C	Tank D	Tank E
Before	3 u	1 u	5x1.7 = 8.5 u
Change	- 1.5 u	- 0.2 u	+ 1x1.7 = + 1.7 u
After	1.5 u	0.8 u	6x1.7 = 10.2 u

Number of guppies that were transferred from Tank C to Tank E
= 50% x 3 u
= ⁵⁰₁₀₀ x 3 u
= 1.5 u

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

20% = ²⁰₁₀₀ = ¹₅

Some guppies from Tank C and Tank D were transferred to Tank E.  The total number of guppies transferred from Tank C and Tank D into Tank E is the same.

Total number of guppies transferred from Tank C and Tank D into Tank E
= 1.5 u + 0.2 u
= 1.7 u

10.2 u = 408

1 u = 408 ÷ 10.2 = 40

Number of more guppies in Tank E than Tank D
= 10.2 u - 0.8 u
= 9.4 u
= 9.4 x 40
= 376

Answer(s): 376