We know, two angles are said to be complementary, if the sum of their measures is 90∘.
Let the angle be x∘ and its complement is 90∘−x∘
According to the statement,
⇒x∘−(90∘−x∘)=40∘
⇒x∘−90∘+x∘=40∘
⇒2x∘=40∘+90∘=130∘
⇒x∘=130∘2=65∘.
Hence, the measure of the angle is x=65∘
and its complement is 90∘−x=90∘−65∘=25∘