Stuck Numbers

function solve(args) {
    var numbers = args.splice(1);
    for (var i = 0; i < numbers.length; i++) {
        numbers[i] = numbers[i].toString();
    }
    console.log(numbers);

    var used = [];
    for (var i = 0; i < numbers.length; i++) {
        for (var j = 0; j < numbers.length; j++) {
            for (var k = 0; k < numbers.length; k++) {
                for (var l = 0; l < numbers.length; l++) {
                    if (numbers[i] != numbers[j] && numbers[k] != numbers[l] && numbers[i] != numbers[k] && numbers[j] != numbers[l]) {
                        if (numbers[i] + numbers[j] === numbers[k] + numbers[l]) {
                            console.log(numbers[i] + "|" + numbers[j] + "==" + numbers[k] + "|" + numbers[l]);
                            if (used.indexOf(numbers[i] + numbers[j] === numbers[k] + numbers[l]) === -1) {
                                used.push(numbers[i] + numbers[j] === numbers[k] + numbers[l]);
                                console.log(numbers[i] + "|" + numbers[j] + "==" + numbers[k] + "|" + numbers[l]);

                            }
                        }
                    }
                }
            }
        }
    }
}

console.log(solve([5, 2, 51, 1, 75, 25]));
console.log(solve([25, 1, 2, 51]));