Use the relationship between supplementary angles ∠a

and ∠b
. What is m∠a if m∠b=121° ?(1 point)
Responses

121°
121 degrees

301°
301 degrees

59°
59 degrees

31°

Since ∠a and ∠b are supplementary angles, their sum is 180 degrees. If m∠b is given as 121 degrees, then m∠a can be found by subtracting 121 from 180:

m∠a = 180 - 121 = 59 degrees

Therefore, the correct answer is 59°.