A light ray coming along the line 3x+4y=5 gets reflected from the line  ax+by=1 and goes along the line 5x−2y=10. Then,

ax+by=1 will be one of the bisectors of the given line. Equation of bisectors of the given lines are 3x+4y−55=±5x−12y−1013 ⇒ 64x−8y=115 or 14x+112y=15⇒a=64115, b−8115 or a=1415, b=12115