01. Sum First and Last

function sumFirstAndLast(arr) {

    let first = Number(arr.shift());
    let last = Number(arr.pop());
    let sum = first + last;
    console.log(sum);

}

ИЛИ:)

function sumFirstAndLast(arr) {

    console.log(Number(arr.shift()) + Number(arr.pop()));

}