In triangle PQR, the lines PS, QT, and RU being medians means they each connect a vertex to the midpoint of the opposite side. The point where medians intersect is known as the centroid of the triangle.
Since PS and QT intersect at point 45, this point is actually the centroid of triangle PQR. The centroid divides each median into two segments, with the segment connecting the vertex to the centroid being twice as long as the segment connecting the centroid to the midpoint of the opposite side.
As for where RU intersects PS, since PS is a median and RU also is a median, they will intersect also at the same centroid point ’45’. Therefore, RU will intersect PS at point 45 as well, which is also the centroid of the triangle PQR.