Black Flag JS Fundamentals

function blackFlag(arr) {
    let days = Number(arr[0]);
    let dailyPlunder = Number(arr[1]);
    let expectedPlunder = Number(arr[2]);

    let collectedPlunder = 0;
    for (let i = 1; i <= days; i++) {
        collectedPlunder += dailyPlunder;

        if (i % 3 === 0) {
            collectedPlunder += dailyPlunder * 0.5;
        }
        if (i % 5 === 0) {
            collectedPlunder -= collectedPlunder * 0.3;
        }
    }
    if (collectedPlunder >= expectedPlunder) {
    console.log(`Ahoy! ${collectedPlunder.toFixed(2)} plunder gained.`);
    } else {
        console.log(`Collected only ${(collectedPlunder / expectedPlunder * 100).toFixed(2)}% of the plunder.`);
    }
}