[tex]
R_1=20\Omega \\
R_2=30\Omega \\
R_3=30\Omega \\
U=2V \\ \\
R_{12}=\dfrac{1}{R_1}+\dfrac{1}{R_2}=\dfrac{R_1R_2}{R_1+R_2}=15\Omega \\
R_{123}=\dfrac{R_{12}R_3}{R_{12}+R_3}=10\Omega \\
I=\dfrac{U}{R_{123}}=\boxed{0.2A}
[/tex]
Hope this helps.
r3t40
