Question

In the accompanying diagram, <1 and <2 are supplementary. What is <3?

Answer 1

since angle 2 is supplementary , angle 2 = 35 degree [ as 35 degree+ angle 1 = 180 degree]
again angle 2 = angle 3 [ vertically opposite angles]
angle 3 is also supplement of angle 1

Answer 2

so whats <1? @digitalmonk

Answer 3

as i said
as 35 degree+ angle 1 = 180 degree
angle 1 = (180 - 35) degree

Answer 4

so 145

Answer 5

yes

Answer 6

Without meaning to imply that the other responses you've rec'd are incorrect, I'll just present an alternative approach here:

First, "supplementary angles" are angles (usually just two) that add up to 180 degrees.

We are told that angles 1 and 3 are supplementary. That means their sum is 180 degrees.

Angle 1 and 35 degrees are supplementary. Therefore, angle 1 is 180-35 = 145 degrees.

Since angles 1 and 3 are supplementary, angle 3 is 35 degrees.

Angles 2 and 3 are equal because both are formed by the same intersecting lines.

therefore, Angle 2 is 35 degrees.