Answer
Current is 2A
Work Step by Step
First find the total resistance of the circuit,
$R = 2Ω + 4Ω + \frac{20Ω\times5Ω}{20Ω + 5Ω} = 10Ω$
Current across the cell can be taken as, $$V = IR$$
$100V = I \times 10Ω$
$I = 10A$
Voltage drop across the 20Ω resistor and 5Ω resistor are same as the are parallel and is also equal to the voltage drop across the equivalent of both these resistors.
Hence current across 20Ω resistor can be found as
$10A\times4Ω= I\times20Ω$
$I=2A$
