Since ∠3 and ∠5 are vertical angles, they are equal. Therefore, we can say:
m∠3 = m∠5.
Given that m∠3 = 67°, we have:
m∠5 = 67°.
Since ∠4 is a supplementary angle with ∠5, we know that the sum of ∠4 and ∠5 is 180°. Thus, we can write the equation:
m∠4 + m∠5 = 180°.
Substituting the value of m∠5 into the equation gives us:
m∠4 + 67° = 180°.
So, the equation you can write to solve for m∠4 is:
m∠4 + 67° = 180°.