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

If the sum and difference of two number are 20 and 8 respectively, then the difference of their squares is: 

Find the value of   $$ {(0.75)^3\over1-.75}+[0.75+(0.75)^2+1]$$

Assume that
$$\sqrt{3} = 3.605 \ (approximately)  $$
$$\sqrt{130} = 11.40 \ (approximately)  $$
Find the value of
$$\sqrt{1.3} + \sqrt{1300}+\sqrt{0.013}  $$

The value of 24 ÷ 4 ×(3 +3) ÷2 is:

Simplify : $$\sqrt{[(12.1)^2-(8.1)^2]÷[(0.25)^2+(0.25)(19.95)]} $$

$$ (17)^{2} + 6 × (13)^{2}-212×6$$

Direction : What value should come in place question mark(?) in the following questions?

0.75 % of 90 + 0.55 % of 80=?