Answer: 7
Step-by-step explanation:
[tex]\dfrac{\overline{CD}+\overline{A F}}{2}=\overline{BE}\\\\\\\dfrac{(18)+(6x-12)}{2}=2x+10\\\\\\(18)+(6x-12)=2(2x+10)\\\\\\6x +6 = 4x +20\\\\2x+6=20\\\\2x=14\\\\\large \boxed{x=7}[/tex]
