Question

What are “DEC” and “CEF” I will mark the brainiest

Answer 1

$\\ \rm\longmapsto <DEC+<CEF=180$

$\\ \rm\longmapsto 11x-12+2x+10=180$

$\\ \rm\longmapsto 13x-1=180$

$\\ \rm\longmapsto 13x=169$

$\\ \rm\longmapsto x=\dfrac{169}{13}$

$\\ \rm\longmapsto x=13$

Now

$\\ \rm\longmapsto 11x-12=11(13)-12=143-12=131$

$\\ \rm\longmapsto 2x+10=2(13)+10=36°$

Answer 2

Answer:

∠ DEC = 142°, ∠ CEF = 38°

Step-by-step explanation:

∠ DEC and ∠ CEF are adjacent angles on the straight line and sum to 180° , so

11x - 12 + 2x + 10 = 180 , that is

13x - 2 = 180 ( add 2 to both sides )

13x = 182 ( divide both sides by 13 )

x = 14

Then

∠ DEC = 11x - 12 = 11(14) - 12 = 154 - 12 = 142°

∠ CEF = 2x + 10 = 2(14) + 10 = 28 + 10 = 38°