Design a rod and beam,with given stresses.

Hello all guys ! Can somebody please explain me how to solve this problem,i got exam which is coming closer and closer with every single day.Probably the problem will be easy for you,but I am new to this science (3-th semester in uni,and this things are new to me)So here is the task,from the exam.
 

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Source: http://image.prntscr.com/image/27c3579d78974d68bf7c7c4921ae3500.png
 

THANKS In advance 3