Answer:
57
Explanation:
Together both angles equal 90
(3x - 15) + (5x -23) = 90
Combine like terms
8x - 38 = 90
Add 38 to both sides
8x = 128
Divide by 8
x = 16
You can check by replacing x with 16 and seeing if it still equals 90.
To find angle MON... replace x with 16
5(16) - 23
Angle MON = 57
I hope this helps!!