We need Net resistance
solve from right words
[tex]\\ \rm\Rrightarrow R_1=20+10=30\Omega[/tex]
[tex]\\ \rm\Rrightarrow \dfrac{1}{R_2}=\dfrac{1}{30}+\dfrac{1}{50}=\dfrac{5+3}{150}[/tex]
[tex]\\ \rm\Rrightarrow R_2=\dfrac{150}{8}=18.75\Omega[/tex]
[tex]\\ \rm\Rrightarrow \dfrac{1}{R_3}=\dfrac{1}{30}+\dfrac{1}{40}=\dfrac{4+3}{120}[/tex]
[tex]\\ \rm\Rrightarrow R_3=\dfrac{120}{7}=17.14\Omega[/tex]
[tex]\\ \rm\Rrightarrow R_{net}=17.14+18.75=35.89\Omega[/tex]
Use ohm's law
[tex]\\ \rm\Rrightarrow I=\dfrac{V}{R}[/tex]
[tex]\\ \rm\Rrightarrow I=\dfrac{9}{35.89}[/tex]
[tex]\\ \rm\Rrightarrow I\approx 0.25A[/tex]
