let x = [
['Jack', 24],
['Sara', 23],
['Peter', 24]
];
// access the first item
console.log(x[0]); // ["Jack", 24]
// access the first item of the first inner array
console.log(x[0][0]); // Jack
// access the second item of the third inner array
console.log(x[2][1]); // 24