#include <iostream.h>
#include <math.h>

void main()
{
double a,b,x;
cout << "Input A: "; cin >> a; cout << endl;
cout << "Input B: "; cin >> b; cout << endl;
cout << "Input X: "; cin >> x; cout << endl;
cout << b*( log(5+a*x)/log(5) ); // (*)
}