Answer:
[tex] \boxed{x\degree = 20\degree} [/tex]
Step-by-step explanation:
Two Angles are Complementary when they add up to 90° (a Right Angle).
[tex] = > x\degree + (3x + 10)\degree = 90\degree \\ \\ = > x\degree + 3x\degree + 10\degree = 90\degree \\ \\ = > 4x\degree + 10\degree = 90\degree \\ \\ = > 4x\degree = 90\degree - 10\degree \\ \\ = > 4x\degree = 80\degree \\ \\ = > x\degree = \frac{80}{4} \degree \\ \\ = > x\degree = 20\degree [/tex]
