Question

if r1 r2 and r3 each of 30 ohm then r1 and r2 are connected parallel and r3 is series with r1 and r2 then wt will be resultant total resistance value

Answer 1

1/Req = 1/R1+1/R2
1/Req = 1/30+1/30
1/Req = 2/30
1/Req = 1/15  
Req = 15 ohms
total resistance = Req + R3
                         = 15 +30
                         = 45 ohms