If , then what is the value of a?

3x² = 36 then what is the value of x?

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

0.75 % of 90 + 0.55 % of 80=?

If  , the value of  is nearest to 

Find the value of

By what least number should 4320 be multiplied so as to obtain a number which is perfect cube? 

On simplification of  

5-[4-{3-(3-3-6)}] is equal to: