#include <iostream>
#include <stdlib.h>
using namespace std;

int main() {
const int n = 10;
int a[2*n+1];
bool b;

srand(time(0));
for (int i = 1; i <= 2*n; i++) {
	a[i]=-20 + (101.0 / RAND_MAX) * rand();
	cout << a[i] << " ";
}
cout <<"\n";

b = true;
for (int i = 1; i <= n; i++){
 if (a[i] != -a[n+i]) b = false;
}
if (b) cout << "а) - верно "; else cout << "а) - неверно "; 
cout <<"\n";

b = true;
for (int i = 1; i <= n; i++){
 if (a[i] != 2*a[n-i]+a[2*n-i+1]) b = false;
}
if (b) cout << "б) - верно "; else cout << "б) - неверно "; 
cout <<"\n";

b = true;
for (int i = 1; i <= n; i++){
 if (a[i]+a[2*n-i+1] <= 17) b = false;
}
if (b) cout << "в) - верно "; else cout << "в) - неверно "; 
cout <<"\n";

b = true;
for (int i = 1; i <= n; i++){
 if (!((a[2*n-i+1]<a[i])&&(a[i]<=a[2*n-i]))) b = false;
}
if (b) cout << "г) - верно "; else cout << "г) - неверно "; 
cout <<"\n";

	return 0;
}

Пример:
39 46 -3 37 32 34 16 65 49 71 29 78 17 60 50 71 28 63 23 4 
а) - неверно 
б) - неверно 
в) - верно 
г) - неверно