Answer:
x=0
Step-by-step explanation:
∵ △ABC~△AED
∴
[tex] \frac{ AE }{ AB } = \frac{ED}{ BC} \\ \frac{4}{10} = \frac{8}{x + 20 } \\ 4x + 80 = 80 \\ 4x = 0 \\ x = 0[/tex]