trig

Triangle PST  is isosceles with PT  = ST

And in a triangle with equal sides, the angles opposite those sides are also equal

So  angle (PST)   = 62

And the sum of the interior angles in triangle PST   = 180

So......

angle (PST)  + angle ( SPT) + angle (PTS)  = 180

62     +     62   +   angle (PTS)  = 180

124   +  angle (PTS)  =  180      subtract 124 from both sides

angle (PTS)  =  56