Answer
$0.060~A$
Work Step by Step
To find the potential difference $\Delta V_2$ across $R_2$, we can consider the potential difference counter-clockwise around the loop including resistor $R_2$ and emfs $\mathscr{E}_1$,$\mathscr{E}_2$, and $\mathscr{E}_3$:
$6.0~V-5.0~V-4.0~V+\Delta V_2 = 0$
$\Delta V_2 = 3.0~V$
We can find the current $i_2$ in $R_2$:
$i_2 = \frac{3.0~V}{50~\Omega} = 0.060~A$
