ILL 1979 Problem 47

Inside an equilateral triangle $ABC$ one constructs points $P, Q$ and $R$ such that $$\angle QAB = \angle PBA = 15^\circ,\\ \angle RBC = \angle QCB = 20^\circ,\\ \angle PCA = \angle RAC = 25^\circ.$$

Determine the angles of triangle $PQR.$