Answer:
9
Step-by-step explanation:
since they're similair then similair sides will be proportional
CB is similair to EF
[tex]\frac{6}{8}[/tex]= [tex]\frac{3}{4}[/tex]
same thing if you try with the hypotenuse AB similair to DE
[tex]\frac{13.5}{18}[/tex]= [tex]\frac{3}{4}[/tex]
So, if you multiply r (DF) by 3/4 you will get the similair side AC
rx 3/4=12
r= 12÷ 3/4
r=16
