Find the exact value of the following question:

$$ 8\sqrt{?}÷14×3+9=21$$

Find the value of $$ {^3\sqrt{\sqrt{.000064}}}$$.

Find the distance between the point (-6, 7) and the point (-1, -5).

If $$ {sin\ θ\ cosec\  θ\over tan θ}=4 $$  then Find the value of tan θ ?

If $$ sin(θ+30^0)= {3\over \sqrt { 12} }  $$ then find cos²θ : 

In ΔABC θ is an acute angle and tanθ is equal to three times of cotθ. Find the value of $$ {sin^{2}θ+cosec^{2}θ-{1\over 2}cot^{2}θ}$$.

If x²+y²-4x-4y+8=0, then the value of x-y is: 

The average age of five girls is 11. The oldest among them is 15 years old. What is the average age of the others?