4thGradeProblem

function solve() {
    let sub = 333;

    for (let index = 598; index > 501; index--) {
        let num = index.toString().split('').sort((a, b) => a.localeCompare(b));
        let result = (index - sub).toString().split('').sort((a, b) => a.localeCompare(b));

        if((index.toString()[1] !== index.toString()[2])
            && (index.toString()[1] !== '5')
            && (index.toString()[2] !== '5')
            && (num.join('') === result.join(''))) {
           return result.join('');
        }
    }
}

console.log(solve()); //259