Understanding Beam Support Reactions: Questioning the Sign Convention

[1question]

Homework Statement

Hi. Question 1-5 from http://www.slideshare.net/hotman1991/met-302-chapter-01 has me puzzled. In the support reactions in F_y, they state B_y + 3.00 - 9.00 = 0. I do not understand why the 3 is positive.

Homework Equations

The Attempt at a Solution

When doing it myself, I took point A as the Pivot point. So I have negative 9 kip (from that 0 to 1.5 kip triangle), B_y, and *negative* 3 kip from the force right beside E. Is there something wrong with my logic?

 

[SteamKing]

The +3 kip load is the reaction at point A. The load of -9 kips comes from the triangular load between points A and B. Remember, the point of this exercise is to find the internal loading of the beam at point B.

 

[1question]

Wow. Cannot believe I messed that up. Crystal clear now, thanks.