If $$ {0.7\over 1-6c}=-0.2$$ then what is the value of c.

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

Given that ( 1² +2²+3²+………..+10²)=385, the value of (2²+4²+6²+……20²) is equal to

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 $$ {a^2\over b}+{b^2\over a}=?$$

The Value of $$ {\sqrt{6-\sqrt{17-2\sqrt{72}}}}$$ is closest to:

Find the value of given equations

$$\left({216\over1} \right) ^{-{2\over3}}÷\left({27\over1} \right) ^{-{4\over3}}=? $$

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

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