parallel circuit I5 =42ma find es if r5=1k?

Answer 1

A diagram would be really really helpful here.

The only thing I can tell you is that, since R5 = 1kΩ, and I5 = 42 mA, then the voltage drop across R5 is V = IR = 1 kΩ × 42 mA = 42 Volts.

But since you didn't post a circuit diagram, I'm not really sure where Es is measured.

If it's TRULY a parallel circuit, with all resistors in parallel with a voltage or a current source, then Es must be in parallel with R5, and therefore it must also have a voltage of 42 Volts.