Tank A contained 2 times as many guppies as Tank B. When 40% of the guppies in Tank A and 10% of the guppies in Tank B were transferred to Tank C, Tank C had 27 guppies, which was 50% more guppies than before. How many more guppies were there in Tank C than Tank B in the end?

	Tank A	Tank B	Tank C
Before	2 u	1 u	2x0.9 = 1.8 u
Change	- 0.8 u	- 0.1 u	+ 1x0.9 = + 0.9 u
After	1.2 u	0.9 u	3x0.9 = 2.7 u

Number of guppies that were transferred from Tank A to Tank C
= 40% x 2 u
= ⁴⁰₁₀₀ x 2 u
= 0.8 u

Number of guppies that were transferred from Tank B to Tank C
= 10% x 1 u
= ¹⁰₁₀₀ x 1 u
= 0.1 u

50% = ⁵⁰₁₀₀ = ¹₂

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

Total number of guppies transferred from Tank A and Tank B into Tank C
= 0.8 u + 0.1 u
= 0.9 u

2.7 u = 27

1 u = 27 ÷ 2.7 = 10

Number of more guppies in Tank C than Tank B
= 2.7 u - 0.9 u
= 1.8 u
= 1.8 x 10
= 18

Answer(s): 18