Question 1208201
.
A cubic container was completely filled with water. When 3/5 of the water was poured 
into a fish tank, the tank was 1/4 full. If the capacity of the tank was 1400 cm^3 more 
than the container, what was the volume of the container.
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        The solution in the post by @mananth is written incorrectly,
        because the setup equation in his post is incorrect.


        I came to bring a correct solution with correct writing.



<pre>
let volume of container be  x

First condition
When 3/5 of the water was poured into a fish tank, the tank was 1/4 full. 

(3/5) x   = (1/4)y

y = (3/5)(4/1) x  = (12/5)x



If the capacity of the tank was 1400 cm^3 more than the container


x + 1400 = y            <<<---===   ! ! !   It is the CORRECT setup equation,
                                            in distinction from that by @mananth

x + 1400 = (12/5)x

multiply equation by 5

5x + 7000 = 12x

7000 = 12x - 5x = 7x

x = 7000/7 = 1000

The volume of the container is 1000  cm^3.    
</pre>

Solved and written correctly.