An investor uses part of z TL in his account to buy gold and the remaining part to buy foreign currency. After some time, the investor sells the gold at a 20\% profit for x TL, and sells the foreign currency at a 20\% loss for y TL.
Accordingly, what is the relationship between $x, y$ and $z$?
A) $3z = 6x + 4y$
B) $5z = 4x + 6y$
C) $4z = 9x + 12y$
D) $6z = 5x + 8y$
E) $12z = 10x + 15y$