C++ :

#include<cstdio>
using namespace std;
int main()
{
	double n,s,n1,n2;
	scanf("%lf",&n);
	if (n<=3) 
	{
	   s=10;
	}
	else 
	{
		if (n<=5)
		{
			s=10+(n-3)*1.8;
		}
		else 
		{
		    s=10+2*1.8+(n-5)*2.7;
		}	
	}
	printf("%.2lf",s);
	return 0;
}

Pascal :

var
n:real;
begin
 read(n);
 if n=0  then write('0.00')
         else if (n>0) and (n<=3) then  write('10.00')
         else if (3<n) and (n<=5) then write(10+(n-3)*1.8:0:2)
                                  else write(10+(5-3)*1.8+(n-5)*2.7:0:2);
end.