### Assume a circuit with two resistors R1 and R2 connected in series with voltage V applied across it.
Total resistance = R1+ R2
Let the total current be I.
Voltage Vin = I.(R1 +R2)
Voltage across R1, V1 = I.R1 = V.R1 / (R1+R2)
Voltage across R2, V2 = I.R2 = V.R2 / (R1+R2)