you must take all the resistor together to make 1 substitutional resistane using the following rules:
1. serial placed resistance: [tex]R_{subst.} = \Sigma R[/tex] and U is divided over the resistors.
2. parallel circuit: [tex]\frac {1} {R_{subst.}} = \Sigma \frac {1} {R}[/tex] and I is divided over the resistors.
