We have to use properties of similar triangle here.

Triangle ACB is similar to AED

\(\frac{AD}{AB} = \frac{DE}{BC}\) => \(\frac{x}{x}+12 = \frac{3}{2}\) => 2x+24 = 3x => x=24

Hence E is the answer

Orrrr

We know Diameter of smaller circle = 4 and Diameter of larger circle = 6

Hence

\(\frac{AB}{AD} = \frac{4}{6}\)

\(\frac{x}{x}+12 = \frac{4}{6}\)

x= 24

E

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