If two angles are complementary and one of them is 77°, what is the size of the other angle?

13°

Step-by-step explanation:

Complementary angles add to 90 degrees, therefore,

∠1+∠2=90

We know one of the angles is 77 degrees, so we can substitute that in.

77 + ∠2=90

Subtract 77 from both sides to solve for the angle

∠2=13

So, the angle is 13 degrees