Примерно решение:

function tickets(input) {
  let counterKids = 0;
  let counterStudents = 0;
  let counterStandards = 0;

  let command;
  while ((command = input.shift()) !== 'Finish') {
    let movie = command;
    let totalSeats = Number(input.shift());
    let usedSeats = 0;

    let ticketType;
    while (usedSeats < totalSeats && (ticketType = input.shift()) !== 'End') {
      usedSeats++;
      if (ticketType === 'kid') {
        counterKids++;
      } else if (ticketType === 'student') {
        counterStudents++;
      } else if (ticketType === 'standard') {
        counterStandards++;
      }
    }
    console.log(`${movie} - ${(usedSeats * 100.0 / totalSeats).toFixed(2)}% full.`);
  }

  let totalTickets = counterKids + counterStudents + counterStandards;
  console.log(`Total tickets: ${totalTickets}`);
  console.log(`${((counterStudents / totalTickets) * 100).toFixed(2)}% student tickets.`);
  console.log(`${((counterStandards / totalTickets) * 100).toFixed(2)}% standard tickets.`);
  console.log(`${((counterKids / totalTickets) * 100).toFixed(2)}% kids tickets.`);
}