1) Draw yourself a diagram and label all 3 points.
2) Select two sides of the triangle and find the midpoint of each.
3) Note that a median is a line joining the vertex of a triangle with the side directly opposite the vertex. Now find the equation of the line that passes through the midpoint of one of the selected sides and which also passes through the opposite vertex of the selected side. Find the equation for the other selected side.
4) Finally find the point of intersection of these two lines by solving the two equations that you derived in 3) simultaneously.