obscure mathamatics problem

Hello there... I've been working on my 2.5d map viewer (not really using any 3d commands, but currently in blitz3d).
I'm having a problem my mathamatics... I need to figure out a way of solving this equation, but I'm not sure it's even possible.

My example:

ry#=10*zoom#*(1/y#)
if ry# = 120, & zoom# = 256 what is y#?
is it it possible to find what something is divided by if we know the answer? I can't figure it out. Please help.

well..Y should be then Y=(10*zoom#)/ry#

WOW!?! really? ha... I feel like an idiot... thankyou very much :)

Really.

You have to multiply each part of equation using the same factor

your equation : ry=10*zoom*(1/y)

step 1 : Factor = *y
ry *y=10*zoom*(y/y)
( y/y=1 ) => ry*y=10*zoom

step 2 factor= 1/ry
y*ry /ry = 10*zoom /ry
simplify the quation. => y= 10*zoom/ry