Answer:
x = 4
Explanation:
You know that B = 100
E = 43 (Vertical angles are congruent)
Since vertical angles are congruent E = 43
Now that you have solved for 2 angles in the triangle you can set up an equation.
The interior angles of a triangle must add up to 180.
100+43+(10x-3)=180
(Simplify)
143+(10x-3)=180
(Subtract 143 from both sides)
10x-3=37
(Add 3 to both sides)
10x=40
(divide through by 10)
x=4
(Sorry if the explanation doesn't make sense. It's a bit hard to explain without a diagram. I hope this helped though!)