Hello, because there is not a circuit I'll explain the voltage divider and make an exercise, this way you can solve the problem using the method described here.
Answer with explanation:
A voltage divider uses the voltage distribution among components to find a voltage in a specific element of the circuit. If we have a source V1 connected to impedances Z1 and Z2 in series, we can use a voltage divider to find the voltage across Z1 or Z2 base on their value and the input voltage.
VZ1 = V1*Z1/(Z1+Z2)
VZ2 = V1*Z2/(Z1+Z2)
In the image, to find the voltage Vo across R2 we apply the following equation: Vo = (V1*R2)/(R1+R2).
To solve the exercise in the other image, we need to apply a voltage divider twice:
In-circuit 1 we are asked to find the voltage VAB that falls on R2 and R3 (the same voltage for both resistances because are in parallel), to do so we use a voltage divider using V1, R1 and RT where RT is the equivalent resistance RT = R2//R3 + R4, therefore, for circuit two VAC = (V1*R1)/(R1+RT). After finding VAC we apply voltage divider again to find VAB, see circuit 3, to do so we apply VAB = (VAC*R2//R3)/(R2//R3 + R4) = (VAC*R2//R3)/(RT)