Question

Here's a link to the question..I have the first one correct butcan't seem to figure out the second question.

http://capa2.phy.ohiou.edu/res/ohiou/ccliphys/dcCircuits/resistors/07_res_series_3unequal.problem

There's also another question..
http://capa2.phy.ohiou.edu/res/ohiou/ccliphys/dcCircuits/resistors/05_res_series_3equal.problem

I can't seem to figure out the last two questions. They're all verysimilar so I'm guessing there's a pretty main concept that I'mmissing.

PLEASE HELPPPP!