Using a mathematical equation, calculates a coffee shop's profit based on the price of the first cup, refill price, cost to make coffee, and number of cups you get, plus how friendly you are with the cashier. Friendliness factor can only be values between 0 and 1.

coffee_profit.js

function profit(firstCup, refillPrice, costToMake, numberOfCups, friendlinessFactor) {
    return (
        (-friendlinessFactor + 1) *
        (Math.pow(numberOfCups, 0) * (firstCup - costToMake) +
            Math.pow(numberOfCups, 0) * (refillPrice * (numberOfCups - 1) - costToMake * (numberOfCups - 1)))
    );
}