Tank A contained 4 times as many guppies as Tank B. When 30% of the guppies in Tank A and 10% of the guppies in Tank B were transferred to Tank C, Tank C had 39 guppies, which was 50% more guppies than before. How many less guppies were there in Tank B than Tank A in the end?

	Tank A	Tank B	Tank C
Before	4 u	1 u	2x1.3 = 2.6 u
Change	- 1.2 u	- 0.1 u	+ 1x1.3 = + 1.3 u
After	2.8 u	0.9 u	3x1.3 = 3.9 u

Number of guppies that were transferred from Tank A to Tank C
= 30% x 4 u
= ³⁰₁₀₀ x 4 u
= 1.2 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
= 1.2 u + 0.1 u
= 1.3 u

3.9 u = 39

1 u = 39 ÷ 3.9 = 10

Number of less guppies in Tank B than Tank A
= 2.8 u - 0.9 u
= 1.9 u
= 1.9 x 10
= 19

Answer(s): 19