Mathematically it would be 8 since BE=CE and CE=4.
I say the answer is d I might be wrong.
-6 because for every value (x,y) there is another value (-x,y) so for the value (6,0) there must also be a value (-6,0). That is what the definition of y-axis symmetry is, it is also known as being an "even" function if it has this type of symmetry. Look at the graph of y=(x^2)-36 to see how this works.
Given are the two points (-10,0) and (-8,20), and equation of the line as y=mx+b.
We can plug the given values in the equation as follows :-
0 = -10m + b .........equation(1)
20 = -8m + b .........equation(2)
Subtracting equation(1) from equation(2)
20 - 0 = (-8m + b) - (-10m + b)
20 = -8m + b + 10m - b
20 = 10m - 8m
20 = 2m
m = 10
Plugging m=10 in the equation(1)
0 = -10(10) + b
0 = -100 + b
b = 100
So final answer is b = 100.