Hello there!
The answer is:
3.1
1.3
.31
.13
Recall the secant-tangent theorem, and you have
EA^2 = EC*CD
12^2 = 8*(x+10)
and now ED = EC+CD = 8+x+10
I suspect a typo somewhere in the murk above
Y - (-8) = -6 (x-2) is correct everything else is not
y + 8 = -6x + 12
y +:8 - 8 = -6x + 12 - 8
y = -6x + 4 is slope intercept form