6 is the answer to the question cuz its the biggest
The middle answer is the only correct one.
The brackets containing 7 have moved. That is, 7 is associated with something different on the left and right sides of the equation. The property that lets you do that is ...
... associative property
_____
Either way you evaluate the equation, it comes out
... 3 + 3 = 10 - 4
... 6 = 6
The appropriate choice is ...
... 6 . . . . . the second selection
So you question is most likely about a triangle DEF with the 3 angles being named D, E, F. The triangle would look something like the image attached below.
If that is what is being asked then i need more info to answer but
By Definition it would be 180 degrees.
We can use quadratic formula to determine the roots of the given quadratic equation.
The quadratic formula is:

b = coefficient of x term = -11
a = coefficient of squared term = 2
c = constant term = 15
Using the values, we get:
So, the correct answer to this question are option B and D