Tank B contained 2 times as many guppies as Tank C. When 10% of the guppies in Tank B and 40% of the guppies in Tank C were transferred to Tank D, Tank D had 120 guppies, which was 25% 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	2 u	1 u	4x0.6 = 2.4 u
Change	- 0.2 u	- 0.4 u	+ 1x0.6 = + 0.6 u
After	1.8 u	0.6 u	5x0.6 = 3 u

Number of guppies that were transferred from Tank B to Tank D
= 10% x 2 u
= ¹⁰₁₀₀ x 2 u
= 0.2 u

Number of guppies that were transferred from Tank C to Tank D
= 40% x 1 u
= ⁴⁰₁₀₀ x 1 u
= 0.4 u

25% = ²⁵₁₀₀ = ¹₄

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
= 0.2 u + 0.4 u
= 0.6 u

3 u = 120

1 u = 120 ÷ 3 = 40

Number of less guppies in Tank C than Tank B
= 1.8 u - 0.6 u
= 1.2 u
= 1.2 x 40
= 48

Answer(s): 48