how to solve this?????????????

Answer: 6.25 cm
Step-by-step explanation:
Area of parallelogram [tex]A=base\times height[/tex]
Using base as AB and height as DE
[tex]Area=8\times 5[/tex]
Now, using base BC and height as DF
[tex]Area=6.4\times x[/tex]
Equating area
[tex]8\times5=6.4\times x\\x=6.25\ cm[/tex]