Answer:
x = 12
Step-by-step explanation:
Quadrilaterals ABCD and FECG are similar, so their corresponding sides would be in the proportion.
[tex] \frac{x}{6} = \frac{5 + 5}{5} \\ \\ \frac{x}{6} = \frac{10}{5} \\ \\ x = \frac{10 \times 6}{5} \\ \\ x = 2 \times 6 \\ \\ x = 12 \: [/tex]
