sumtotal.js

const lineItems = [
  { name: 'Carmenere', price: 35, quantity: 2 },
  { name: 'Cabernet', price: 50, quantity: 1 },
  { name: 'Merlot', price: 98, quantity: 10 },
];


const sumTotal = lines => {
  let total = 0;
  
  for(let i = 0; i < lines.length; i++) {
    total += lines[i].quantity * lines[i].price;
  }
  
  return total;
}

console.log(sumTotal(lineItems)); // 1100