back to the past *edited*

function backToThePast(input) {
    let inheritance = Number(input[0]);
    let endYear = Number(input[1]);

    let age = 17;

    for (let i = 1800; i <= endYear; i++) {
        age++;
        if (i % 2 === 0) {
            inheritance -= 12000;
        } else if (i % 2 === 1) {
            inheritance -= 12000 + 50 * age;
        }
    }

    if (inheritance >= 0) {
        console.log(
            `Yes! He will live a carefree life and will have ${(inheritance).toFixed(2)} dollars left.`);
    } else {
        console.log(`${Math.abs(inheritance).toFixed(2)}`);
    }
}
backToThePast([100000.15, 1808])