Question

What is the measure of the unknown angle?

Answer 1

138°

Explanation:

We can assume this is a straight line, and straight lines form 180°.

Therefore 42° and n are supplementary angles, which mean that they add up to 180°. We will use this information to create an equation.

42° + n = 180°

Now, we can use it as a regular equation and work backwards to find out what n is.

Subtract 42° on both sides

n = 138

n = 138°

Answer 2

138°

Explanation:

let the unknown angel be X

Now,

or, x+42=180

or,x=180-42

or, X=138° answer