Answer:
42 degrees and 48 degrees
Explanation:
If they are complementary, that means they add up to 90 degrees, so
4x + 5x - 18 = 90,
Solving,
9x - 18 = 90
add 18 to both sides
9x = 108
divide both sides by 9
x = 12
Now, to find the angle measures of each you have to substitute x = 12 into both angles.
4x --> 4 * 12 = 48 degrees
5x - 18 --> 5 * 12 - 18 --> 60 - 18 --> 42 degrees