Use the relationship between supplementary angles ∠a and ∠b. What is m∠a if m∠b = 121°? (1 point)
121°
301°
59°
31°
Since supplementary angles add up to 180 degrees, and it is given that angle b is 121 degrees, angle a must be 180 - 121 = 59 degrees.
Therefore, m∠a = 59°.