Let point of reflection is (0,y) then, by law of reflection, Angle of incidence = Angle of reflection ⇒tan‌θ=tan(−θ) { As angles are measured in opposite directions.} ⇒‌‌m1=−m2 ⇒‌‌‌
y−3
−2
=‌
y−10
5
⇒‌‌5y−15=−2y+20 ⇒‌‌7y=35,y=5 So, point is (0,5).