Solving voltage dividers with unknown resistance
Jonk and Spehro gave you some good hints, but maybe you need a schematic.
Sometimes there are tricks to help you solve a problem, sometimes not. If you don't see a quick way, do it the old fashioned way.
Realize that with a series current source, whatever is feeding that current doesn't matter.
Redraw in the simplest form possible, using standard symbols wherever possible.
Label the nodes.
Write equations.
Solve.



simulate this circuit &ndash; Schematic created using CircuitLab