To determine the measure of angle \( m∠7 \), we need more context about the relationship between angles 6 and 7.
If angles 6 and 7 are supplementary (they sum to 180°), then:
\[ m∠7 = 180° - m∠6 = 180° - 140° = 40°. \]
If angles 6 and 7 are congruent (equal), then:
\[ m∠7 = m∠6 = 140°. \]
Without additional information, the most common assumption in geometry problems involving angles is that they could be supplementary.
So, if we assume that angle 6 and angle 7 are supplementary, the answer would be:
40°.