Question 666165
If the angle is x, then the complement is 90 - x.  Then we just translate:

The complement of an angle (90 - x) is (=) 10 degrees less (- 10) than the angle itself (x). Find the angle and its complement.
90 - x = x - 10
90 = 2x - 10  (added x to both sides)
100 = 2x (added 10 to both sides)
x = 50 (divided both sides by 2)