From the given diagram we get that the lines marked with the arrow are parallel, then the two triangles are similar.
To answer this question we will use the following diagram as a reference:
Therefore:
[tex]\frac{?}{18}=\frac{9-4}{9}.[/tex]
Simplifying the above result we get:
[tex]\frac{?}{18}=\frac{5}{9}.[/tex]
Multiplying the above result by 18 we get:
[tex]\frac{?}{18}\times18=\frac{5}{9}\times18.[/tex]
Simplifying the above result we get:
[tex]\begin{gathered} ?=\frac{90}{9}, \\ ?=10. \end{gathered}[/tex]
Answer:
[tex]?=10.[/tex]
