♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️
Sum of the interior angles of any triangle is 180° .
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Thus ;
[tex]In \: \: ∆ DEF→D + E + F = 180° \\ [/tex]
[tex]D + 77° + 31° = 180°[/tex]
[tex]D + 108° = 180°[/tex]
Subtract sides 108°
[tex]D + 108° - 108° = 180° - 108° \\ [/tex]
[tex]D = 72°[/tex]
♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️
The correct answer is Option four .
♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️♥️
