A.
you can find the angle measures of the big triangle and then find it’s corresponding angle.
For sake of convenience, reverse the series, then it would be:
21,19,17.....7
a=21, d = -2,
s(4) = 4/2 (21+15)
s(4)=2(36)
s(4) = 72
She is wrong she should have added 18 to both sides
Answer:
<em>Answer is </em><em>given below with explanations</em><em>. </em>
Step-by-step explanation:

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Answer:
x = 60° (Alternate angles)
Step-by-step explanation:
a) x = 60°
b) Reason: Alternate angles