Answer
The current at point $a$ is $~~3.75~A$
Work Step by Step
The equivalent resistance of $R_1$ and $R_2$ in series is $20.0~\Omega+10.0~\Omega$ which is $30.0~\Omega$
We can find the equivalent resistance of $R_1$ and $R_2$, along with $R_1$ which is in parallel:
$\frac{1}{R_{eq}} = \frac{1}{20.0~\Omega}+\frac{1}{30.0~\Omega}$
$\frac{1}{R_{eq}} = \frac{3}{60.0~\Omega}+\frac{2}{60.0~\Omega}$
$R_{eq} = 12.0~\Omega$
We can find the equivalent resistance in the circuit:
$R_{eq} = 20.0~\Omega+12.0~\Omega = 32.0~\Omega$
We can find the current in the circuit:
$i = \frac{120~V}{32.0~\Omega} = 3.75~A$
The current at point $a$ is $~~3.75~A$
