Given that angles \( \angle 1 \) and \( \angle 2 \) are supplementary, you can express this relationship mathematically. If \( m\angle 1 = 77^\circ \), you can set up the following equation for \( m\angle 2 \) (let's denote \( m\angle 2 \) as \( x \)):
\[ x + 77 = 180 \]
This equation expresses that the sum of the measures of the two angles equals \( 180^\circ \), since supplementary angles add up to \( 180^\circ \).
Now, you can solve for \( x \):
- Subtract \( 77 \) from both sides:
\[ x = 180 - 77 \]
- Calculate:
\[ x = 103 \]
So, \( m\angle 2 = 103^\circ \).
The other equations you mentioned, such as \( x = 90 - 77 \) or \( x + 77 = 90 \), are not relevant to solving for \( m\angle 2 \) in this case since they do not accurately represent the relationship between supplementary angles. The correct equation is:
\[ x + 77 = 180 \]
And the solution yields \( m\angle 2 = 103^\circ \).