excursion.js

function excursion(input) {
    let index = 0;
    let tourists = Number(input[index]);
    index++;
    let nights = Number(input[index]);
    index++;
    let maps = Number(input[index]);
    index++;
    let tickets = Number(input[index]);
    index++;
    let nightPrice = 20;
    let mapPrice = 1.60;
    let ticketPrice = 6;
    let expenses = 0.25;

    let touristCosts = (nights * nightPrice) + (maps * mapPrice) + (tickets * ticketPrice);
    let groupCosts = tourists * touristCosts;
    let total = groupCosts + (groupCosts * expenses);

    console.log(total.toFixed(2));
}

excursion(["20", "14", "30", "6"]);