dc circuits problem, need help solving please?

[maticulously_happy]

18v +----------R------(splits to || . all || ) 600 ohm(0.6k ohm) || 1.8k ohm || 3.6k ohm---(

|-------R---|----------|------------|
18v ``````0.6k``````1.8k``````3.6k
|------------|-----------|-----------|


engineer better engineers.
thnaks!!!