Sale[] is a list. A tuple has a fixed length.

Goal

Log the first city and a pair.

const cities: string[] = ["Nairobi", "Mombasa", "Kisumu"];
console.log(cities[0]);
console.log(cities.length);

interface Sale { city: string; units: number }
const rows: Sale[] = [
  { city: "Nairobi", units: 12 },
  { city: "Kisumu", units: 5 },
];
console.log(rows[1].units);

const pair: [string, number] = ["Nakuru", 4];
console.log(pair[0], pair[1]);

const units: number[] = [12, 8, 5];
console.log(units.reduce((a, n) => a + n, 0));