Answer :

Answer:

56.4 degrees

Step-by-step explanation:

To find mED, we need to use the angle sum property of a triangle, which states that the sum of the angles in a triangle is 180 degrees. In this case, we have angles E, B, and C in triangle EBC.

1. Set up the equation:

mED + mBF + mBCF = 180

2. Substitute the given expressions into the equation:

(9x - 3) + (15x - 39) + (11x - 9) = 180

3. Combine like terms:

9x - 3 + 15x - 39 + 11x - 9 = 180

35x - 51 = 180

4. Solve for x:

35x = 231

x = 231/35

x = 6.6

5. Substitute x back into the expression for mED:

mED = 9x - 3

mED = 9(6.6) - 3

mED = 59.4 - 3

mED = 56.4

Therefore, mED is 56.4 degrees.