function part2(idName, btnAdd) {

    var part2 = document.getElementById(idName);
    var btn = document.getElementById(btnAdd);
    if (part2.className == 'hidden') {
        part2.className = 'visible';
        btn.src = "Images/Calculator/coins_delete.png";
    } else {
        part2.className = 'hidden';
        btn.src = "Images/Calculator/coins_add.png";
    }
}