Step 1

Solving by similarity of triangle

Step 2

\(\displaystyle{9}{n}\triangle{A}{B}{C}{\quad\text{and}\quad}\triangle{C}{D}{E}\),

\(m<ABC=m<CDE\) (Given)

\(\displaystyle{\quad\text{and}\quad}{m}<{A}{C}{B}={m}<{D}{C}{E}\)

So \(\displaystyle\triangle{A}{B}{C}\) is similar to \(\displaystyle\triangle{C}{D}{E}\).

\(\displaystyle\Rightarrow\frac{{{A}{B}}}{{{D}{E}}}=\frac{{{C}{B}}}{{{C}{D}}}\)

\(\displaystyle\Rightarrow\frac{5}{{{7}\cdot{5}}}=\frac{x}{{3}}\)

\(\displaystyle\Rightarrow{x}=\frac{15}{{{7}\cdot{5}}}={2}\)

x=2