Answer:
4:5
Explanation:
A pair of complementary add up to 90, given that one of them is 50, we can do this: x + 50 = 90
solve it and we get x = 40
40 + 50 = 90, so 40 and 50 are the pair of complementary angles.
As for it's Ratio, we can just get the pair and have it as 40:50 but we can reduce it to 4:5