Answer:

Step-by-step explanation:
Combine Similar Elements: 

Combine Similar Elements: 

Subtract 14 From Both Sides

Simplify

Add
To Both Sides

Simplify

Divide Both Sides By 

Simplify

Let f(x)=0, you'll get x=3 and x=-5, those are the x-intercepts of the function.
Remark
I would have had the answer a whole lot sooner if I would have read the question properly. The figure in the circle is called a cyclic quadrilateral. It has the odd property that the angles that are opposite each other add up to 180o.
So DEB + DCB = 180o
DEB = 180 - 87
DEB = 93o
Note: The arcs marked 60 and 76 have nothing whatever to do with this problem.