Answer:
140°
solution,
Let <DEF= x°
<CDE= 2x°
<BAF= 90°
The sum of interior angle of hexagon= 720°
<A + <B + <C + <D + <E +<F = 720°
[tex]90 + 145 + 115 + 2x + x + 160 = 720 \\ 510 + 3x = 720 \\3x + 510 = 720 \\ 3x + 510 - 510 = 720 - 510 \\ 3x = 210 \\ \frac{3x}{x} = \frac{210}{3} \\ x = 70 \: degree[/tex]
Again,
[tex] < \: cde = 2x \\ \: \: \: \: \: \: \: \: \: \: \: \: = 2 \times 70 \\ \: \: \: \: \: \: \: \: \: \: \: \: = 140 \: degree[/tex]
Hope this helps...
Good luck on your assignment..
