[(169×121)÷(11×13)]-3=?

Simplify the following equations.
1 ÷[{p²/(p+6)}+{6p/(p+6)}]

If $$ {1\over3} ({12x\over5}-{1\over2})+{6\over5}={7\over6}$$ then what is the value of x?

Simplify the following equation.
$${(785.785.785+435.435.435) \over(785)^{2}+(435)^{2}-(785)(435)}$$

Simplify the following equation.
$$ {(100)}^{1\over2}.{(0.001)}^{1\over3}-{(0.0016)}^{1\over4}.{3}^{0}+({5\over4})^{-1} $$

If a 12 meter rod is cut into 25 equal pieces, what is the length of each piece?

What should come in place of the question mark (?) in the following question?
19.5% of 524 = 50% of ?

What approximate value should come in place of the question mark (?) in the following question? 
21.9714 × (8.8749 - 4.9393) = ?