Simplify : $$ {5\over3}×{7\over51}\ of \ {17\over5}-{1\over3}\over {2\over9}×{5\over7}\ of \ {28\over5}-{2\over3}  $$

Direction: what should come in place at question mark(?).

$$ {\sqrt{4489}+(71)^{2}-(?)^{2}=2707}$$

Find the value of $$ {5^{1\over2}-[3^{1\over4}+6-4÷2]}$$

Evaluate: $${-(4-6)^2-3(-2)+।-6।\over 18-9÷3×5}$$

If $$ a={{\sqrt{3}+\sqrt{2}}\over {\sqrt{3}-\sqrt{2}}}$$ and $$ b={{\sqrt{3}-\sqrt{2}}\over {\sqrt{3}+\sqrt{2}}}$$, then find the value  of $$ {a^2\over b}+{b^2\over a}=?$$

If $${a+b=10}$$ and $$ \sqrt{a\over b}-13=-\sqrt{b\over a}-11$$, then what is the value of $${3ab+4a^2+5b^2}$$?

If $${{k^2}\over {k^2-2k+1}}={1\over 6}$$, then what is the value of $${1\over k^3}+k3$$ ?

What is the value of $$ {0.55 × 4.5\over 0.81}$$ ?