Help with a simple code

[ilikewomen5678]

Ok. Hi thanks for taking the time to read this. I have just started doing boolean , and I understand the logic of an if statement, but I made this code to tell someone if the customer is 21 or not based on only the birth year. I assumed that in the part of my code that is -- if (isLA <= 21)--. I was wondering why it is a less than or equal sign that only makes it have the results I want. But I believe it should be a greater than or equal sign. when I use the greater than or equal sign it does not work correctly. Am I not understanding something here? I use excel a lot and I know the logic behind an if statement.

 #include "stdafx.h"
#include <iostream>

bool isAge(int x, int y)
{
	return (x - y);
}


int main()
{
	std::cout << "Enter the current year: ";
	int x;
	std::cin >> x;

	std::cout << "Enter the customer's birth year: ";
	int y;
	std::cin >> y;

	bool isLA = isAge(x, y); // legal age
	if (isLA <= 21)
		std::cout << "Customer is 21" << std::endl << std::endl;
	else
		std::cout << "Customer NOT 21" << std::endl << std::endl;

		return 0;
}

[cire]

isLA is of type bool. Variables of type bool cannot take on any values other than false (0) and true (1), both of which will compare less than or equal to 21.