Consider the following frequency distribution :

Class :	0-6	6-12	12-18	18-24	24-30
Frequency :	$$a $$	$$b$$	12	9	5

If mean = $${{309} \over {22}}$$ and median = 14, then the value (a $$-$$ b)² is equal to _____________.

The sum of all the elements in the set {n$$\in$$ {1, 2, ....., 100} | H.C.F. of n and 2040 is 1} is equal to _____________.

The area (in sq. units) of the region bounded by the curves x² + 2y $$-$$ 1 = 0, y² + 4x $$-$$ 4 = 0 and y² $$-$$ 4x $$-$$ 4 = 0, in the upper half plane is _______________.

Let f : R $$\to$$ R be a function defined as $$f(x) = \left\{ {\matrix{ {3\left( {1 - {{|x|} \over 2}} \right)} & {if} & {|x|\, \le 2} \cr 0 & {if} & {|x|\, > 2} \cr } } \right.$$

Let g : R $$\to$$ R be given by $$g(x) = f(x + 2) - f(x - 2)$$. If n and m denote the number of points in R where g is not continuous and not differentiable, respectively, then n + m is equal to ______________.