Respuesta :

Answer:

56°

Step-by-step explanation:

1. the rule is: m(DCE)+m(DEC)+m(CDE)=180;

2. m(DCE)=180-(7x-2)=182-7x;

m(DEC)=180-(4x+33)=147-4x;

m(CDE)=180-(9x-31)=211-9x;

3. after the substitution all the angles (item 2) into the rule (item 1):

182-7x+147-4x+211-9x=180;

20x=360;

x=18;

4. if x=18, then filally, m(DCE)=182-7*18=56°.

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