Answer:
mRJN = 75°
Explanation:
VJA = 15°
If the line VJ would continue through J and stop at a point that we now call Z. Then the new angle ZJN which is a vertically opposite angle to VJA would also be 15°
Angle VJE is supplementary to VJR and therefore also 90°
And if angle VJE is 90°, that means its supplementary angle EJZ is also 90°.
Angle EJN (supplementary to RJN) is simply EJZ - ZJN = 90° - 15° = 75°