when it asks for the speed limit, it asks twice, and I'm unsure of how to fix that. Secondly, when I enter something outside of the input validation parameters, I get an endless loop error

So I have this code, and everything runs fine when I'm within the parameters of the input validation. But, I am having two issues with this code. First off, when it asks for the speed limit, it asks twice, and I'm unsure of how to fix that. Secondly, when I enter something outside of the input validation parameters, I get an endless loop error. Any advice as to how to fix these problems? I'm not a c++ expert, I'm rather new at the whole thing, so help would be greatly appreciated

#include <iostream>
#include <string>

float getSpeed(double speedLimit, double speed, double calcSpeed, double overSpeed);

using namespace std;

const int lowSpeed = 20;
const int highSpeed = 70;

int main()

{

double speedLimit, speed, calcSpeed, overSpeed();
{

cout << "Enter the speed limit: " ;
cin >>speedLimit;
}
while (speedLimit <=lowSpeed || speedLimit >= highSpeed)

cout << "ERROR: the speed limit must be between, 20 mph and 70 mph." << endl;
cout << "Enter the speed limit." <<endl;
cin >>speedLimit;

cout << "Enter your speed:"<< endl;
cin >> speed;

calcSpeed = speed - speedLimit;

cout << "You were going " ;
cout <<calcSpeed;
cout <<"mph over the speed limit.";
return 0;}