Hello, spaarky!

A challenging problem . . . I haven't solved it yet.

This how I envision the two tanks and the water.

Code:

Tank X Tank Y
* *
| |
| | * *
| | | |
* - - - * * - - - - - *
|:::::::| |:::::::::::|
h|:::A:::| h|:::::B:::::|
|:::::::| |:::::::::::|
*-------* *-----------*

There are liters of water in tank

There are liters of water in tank

We know that: .

We see that: . is 4 more than the capacity of tank

. . Hence, the capacity of tank is 64 liters.

We know that is 40% of the capacity of tank

I need at least one more equation . . . Where is it?