Finding the current in a resistor

[Maddy315]

Find the current across the 20 Ω resistor using the image.
http://s1078.photobucket.com/albums/w488/maddy31595/?action=view&current=Untitled.jpg
So my teacher gave us this problem and the answer, but didn't go over how to get the answer. I have no idea where to even start. Help?

 

[SammyS]

Find the current across the 20 Ω resistor using the image.
http://s1078.photobucket.com/albums/w488/maddy31595/?action=view&current=Untitled.jpg
So my teacher gave us this problem and the answer, but didn't go over how to get the answer. I have no idea where to even start. Help?

... and what answer did your teacher give you ?

 

[Maddy315]

Oops sorry. He gave it to us right as the bell rang so I didn't get it down. But I believe it was .2 ?

 

[SammyS]

Do you know how resistances add in series?

Do you know how resistances add in parallel?