ok so we have 5 ohm and 20 ohm , in parallel, which are both in series with 50ohm
now for equivalent resistance in parallel
1 / R eq= 1/R1 + 1/R2
ie R eq= R1 * R2 / ( R1+R2)
therefore we have ( 4ohm in series with 50 ohm)
then R eq= 54ohm ( add them when in series )
then apply v=IR to get total current in circuit
I= V/R
= 12 / 54
now when this current gets to the section where it splits in two, the current is divided and the majority of current goes throguh the least resistance
current through 5ohm = 20 / ( 25) * 12 / 54
current through 20ohm = 5 / ( 25) * 12/54