when open circuit, current in left side = 20/(5+15)= 1A
voltage at A = 1*15 = 15 V
voltage at B = 15-7=8
current in the left side of cct = 8/8 = 1 A
source voltage = 1A*(8+2) =10 V
when open circuit, current in left side = 20/(5+15)= 1A
voltage at A = 1*15 = 15 V
voltage at B = 15-7=8
current in the left side of cct = 8/8 = 1 A
source voltage = 1A*(8+2) =10 V