One angle is 40 degrees and the other is 50 degrees.
A complementary angle is 90 degrees.
As the ratio is 4:5 we can use the equation: 4x+5x=90
Solving it we get:
9x=90
x=10.
So the ratio is 4(10):5(10)
Meaning the two angles are 40 degrees and 50 degrees.
I hope this helps!
(And if you can, could I have brainliest please?)