Answer:
[tex]\huge\boxed{\sf x = 18\°}[/tex]
Explanation:
If ∠ABC and ∠DEF are complementary angles, this means they add up to 90 degrees.
So,
∠ABC + ∠DEF = 90°
72 + x = 90
Subtract 72 to both sides
x = 90 - 72
x = 18°
[tex]\rule[225]{225}{2}[/tex]
