To solve for the value of \( m∠2 \) given that \( m∠1 = 87° \), we can use the properties of vertical angles and supplementary angles mentioned in the problem.
Since \( ∠1 \) and \( ∠3 \) are vertical angles, they are equal. Therefore,
\[ m∠3 = m∠1 = 87° \]
Next, since \( ∠2 \) and \( ∠3 \) are supplementary, we have:
\[ m∠2 + m∠3 = 180° \]
Substituting \( m∠3 = 87° \) into this equation gives us:
\[ m∠2 + 87° = 180° \]
If we let \( m∠2 = x \), we can write the equation as:
\[ x + 87° = 180° \]
Therefore, the correct equation to solve for \( m∠2 \) is:
x + 87° = 180°