We can form two ratios to help us solve this:
(2x+6):10 = (x+6):8
(2x+6)         (x+6)
---------   =   --------
   10              8
Cross multiply:
8(2x+6) = 10(x+6)
Foil: 
16x + 48 = 10x + 60
Move like variables to the same side: 
16x - 10x = 60 - 48
6x = 12
x = 2
Line AE = 2x+6
Plug 2 for x into the equation: 2(2) + 6 = 10
Hope this helps, and May the Force Be With You!
-Jabba