The value of   $${(75.8)^2-(55.8)^2\over20}$$

Simplification the following equations

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

0.75 % of 90 + 0.55 % of 80=?

Simplification the following equations shown below

What approximate value should come at place of the question mark(?) in the following question?

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

125% of 2440 – 75% of 1856 = ?

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