Let two ordinate of the other end R be Y Coordinates of other end R are (10,y) i.e., R(10,y)
Distance PR=10 [given]
Squaring both sides
⇒ 100=73+y2+6y
⇒ y2+6y+73-100=0
⇒ y2+6y-27=0
Splitting the middle term
⇒ y2+9y-3y-27=0
⇒ y(y+9)-3(y+9)=0
⇒ (y+9)(y-3)=0
⇒ y= -9, y=3