Can "solvo" be used as solution ( a mixture in a liquid form) as in most languages? For example: segnoro Jekyll trinkis la solvo kaj li transformiĝis en segnoro Hyde.
I translated this as "He uses the theory for the solution," which I think is disgustingly loose -- should be "to find the solution." Is this sentence equally bad in Esperanto?
No, it isn’t. I do not think that it is necessary to use trovi unless you want to start a philosophical discussion whether you find an existing, but unknown or hidden solution, or whether you create a new solution that has not existed before.