Question 253785
Let the required angle be x.
The its complementary angle = 90-x
Given, x/(90-x) = 4/5
             5x = 4*(90-x)
             5x = 360-4x
          5x+4x = 360
             9x = 360
              x = 360/9
              x = 40degrees
Its complementary angle = 90-40 = 50 degrees