Answer: d=70; f=45; e=65
Explanation:
NUMBER 1 WAY
110+d=180
d=70
135+f=180
f=45
d+f+e=180
70+45+e=180
e=65
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NUMBER 2 WAY
concept to know: exterior angle theorem
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System of equation
d+e=135
f+e=110
d+e+f=180
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d=135-e
f=110-e
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d+e+f=180
(135-e)+e+(110-e)=180
135-e+e+110-e=180
245-e=180
e=65
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d=70
e=65
f=45