Final answer:
To find m28 when given that L7 is a supplement and m27 equals 109°, we use the fact that supplementary angles sum to 180°. Subtracting 109° from 180° gives m28 as 71°.
Step-by-step explanation:
To find m28, which is the measure of angle 28, given that L7 is a supplement of 28 and that m27 is 109°, we must first understand that supplementary angles add up to 180°. Since L7 is supplementary to angle 28, we can write the following equation:
m28 + m27 = 180°
Plugging in the given value m27 = 109°, we have:
m28 + 109° = 180°
Subtracting 109° from both sides gives us:
m28 = 180° - 109°
m28 = 71°