Voltage Drop using the Voltage Divider Formulas

Chapter 3 concept..?? **Voltage across a resistor** V_C = 0 Examples: *Find V_R1= V_a - V_b = R1/(R1 + R3) =3V *Find V_R3= V_B - V_C --> V_R3 = V_B >>VOLTAGE DIVIDER concept >> VOLTAGE DROP concept ?? Grd at C or E is the same?? How does multiple sources affect the voltage source?