in triangle ABC, AP perpendicular BC, CQ perpendicular AB and BR perpendicular AC, prove that angle OPQ=angle OPR

The party planning committee has to determine the number of tables needed for an upcoming event. if a square table can fit 8 people and a round table can fit 6 people, the equation 150 = 8x + 6y represents the number of each type of table needed for 150 people.