ciclosAnidados.js

// for 
var alumno = [
  [10, 8, 4, 6, 9],
  [10, 8, 4, 6, 8],
  [10, 8, 10, 6, 8],
  [10, 9, 10, 10, 10]
];

var materias = 0;
var sumCal = 0;
var reprobado = false;

loop1:
for (var i = 0; i < alumno.length; i++) {
  //   console.log(alumno[i]);
  loop2:
  for (var j = 0; j < alumno[i].length; j++) {
  //     console.log(alumno[i][j]);
    if (alumno[i][j] >= 6) {
      sumCal += alumno[i][j];
      materias++;
    } else {
      reprobado = true;
      console.log('reprobado');
      break loop1;
    }
  }
}
if (!reprobado) {
  console.log('alumno aprobado')
  console.log(sumCal / materias);
} else {
  console.log('alumno reprobado por burro');
}