[tex]\begin{gathered} \text{ By Tales' theorem, we know that} \\ \frac{10}{25}=\frac{x}{5}\text{, now since the 5 is dividing, we pass it to multiply at the other side} \\ \frac{10\cdot5}{25}=x \\ x=\frac{50}{25} \\ x=2 \end{gathered}[/tex]
Thus the horizontal distance of the smaller triangle is 2.
