Tank B contained 4 times as many guppies as Tank C. When 20% of the guppies in Tank B and 30% of the guppies in Tank C were transferred to Tank D, Tank D had 132 guppies, which was 20% more guppies than before. How many less guppies were there in Tank C than Tank B in the end?

	Tank B	Tank C	Tank D
Before	4 u	1 u	5x1.1 = 5.5 u
Change	- 0.8 u	- 0.3 u	+ 1x1.1 = + 1.1 u
After	3.2 u	0.7 u	6x1.1 = 6.6 u

Number of guppies that were transferred from Tank B to Tank D
= 20% x 4 u
= ²⁰₁₀₀ x 4 u
= 0.8 u

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

20% = ²⁰₁₀₀ = ¹₅

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

Total number of guppies transferred from Tank B and Tank C into Tank D
= 0.8 u + 0.3 u
= 1.1 u

6.6 u = 132

1 u = 132 ÷ 6.6 = 20

Number of less guppies in Tank C than Tank B
= 3.2 u - 0.7 u
= 2.5 u
= 2.5 x 20
= 50

Answer(s): 50