How are you arriving at these numbers? And what happened to the 200 kN concentrated point load? The UDL of 50 kN per m acts over 9 feet, not 18 feet, and its resultant lies at its cg. The triangular distribution has a resultant of 225 kN, yes, but you show it acting in the wrong location. It too acts at the cg of the triangle.
Here is the Simply Supported Beam with a uniform and triangular load.
The Attempt at a Solution
RAy + RBy = 900 + 225 = 1125kN
ƩMA = 4.5(225) + 12(900) - 18(RBy) = 0
RBy = 656.25kN
RAy = 568.75kN
Is what I've done right so far? (Finding Reactions at A and B)