Keep The Change

function solve(input){
    var bill = Number(input[0]);
    var mood = input[1];
    var drunkTip = bill * 15 / 100;
    var power = (drunkTip.toString().charAt(0));

    switch (mood) {
        case 'happy':
            bill = bill + (bill * 10/100);
            break;
        case 'married':
            //5 -> 0.05
            bill = bill + (bill * 0.05/100);
            break;
        case 'drunk':
        // bill = bill + ....
            bill = bill + Math.pow((bill * 15 / 100), power);
            break;
        default:
            bill = bill + (bill * 5 / 100);
            break;
    }
    var tip = bill- Number(input[0]);
    console.log(tip.toFixed(2));
}