Code:
void display_statement (double, double, double, double, int, double);

}

{
	double x;

	x = Tinterest_paid(200000, 150000);
	printf("The result is\n\n %f', X);

		return 0;



}
What in the world is going on here? First of all, your braces are all screwed up. Secondly, you need to include variables names in the function parameter list - not just their types. Thirdly, you have a semicolon after the function declaration. Or is this even a function declaration? I can't really tell.

Also, how are you using a namespace in a C program? If you intended for this to be C++, then post it in the appropriate forum.

And then there seems to be these mysterious blocks of code which don't exist in any function. You need to stop what you are doing, and spend some time reading some C tutorials.

Code:
#using <mscorlib.dll>
Are you kidding me?...