The triangles are similar. What is the value of x?

Answer:
The value of x is [tex]16\ units[/tex]
Step-by-step explanation:
we know that
If two figures are similar , then the ratio of its corresponding sides is equal
In this problem
[tex]\frac{x}{4}=\frac{12}{3}=\frac{20}{5}[/tex]
therefore
[tex]\frac{x}{4}=4[/tex]
[tex]x=16\ units[/tex]