wra.js

function possibilities(numbers, remaining, expression) {
    if (remaining < 0) {
        return 0;
    } else if (remaining === 0) {
        console.log(expression.join(' + '));
        return 1;
    }

    var result = 0;

    numbers.forEach(function(number, index) {
        var maxTimes = Math.floor(remaining / number);
        for (var numberOfTimes = 1; numberOfTimes <= maxTimes; numberOfTimes++) {
            result += possibilities(numbers.slice(index + 1), remaining - numberOfTimes * number, expression.concat([numberOfTimes + "x" + number]));
        }
    });

    return result;
}

possibilities([100, 50, 25, 10, 5], 250, []);