Answer:
m∠F = 66°
m∠D = 57°
Explanation:
It looks like you have ...
∠D = ∠E = (4x +1)°
∠F = (5x -4)°
The sum of the angles in the triangle is 180°, so we have ...
2(4x +1) +(5x -4) = 180
13x -2 = 180
x = 182/13 = 14
Then the angle measures are ...
∠D = ∠E = (4(14) +1)° = 57°
∠F = (5(14) -4)° = 66°
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m∠F = 66°
m∠D = 57°