Answer:
Step-by-step explanation:
Step 1) Combine all resistors into an equivalent overall resistor. These are all in series so you just add them up. Req = 10Ω + 20Ω + 30Ω = 60Ω: 
 
 
 
 
 
Step 2) Using Ohm's Law, I = V/R = 120/60 = 2 A 
 
Now you know how much current is flowing, and that current flows through each resistor the same. So the current in the 30 Ω resistor is 2.00 amps.