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Solution:
By similar triangles:
\[\frac 1x = \frac x4\]
\[\Rightarrow x=2\]
Again by similar triangles, we can prove 'a', '2a', '4a' lengths.
\[a + 4a = 3\]
\[\Rightarrow a = \frac35\]
Area:
\[A = \frac{(5a)(2a)}2 = \frac95\]