var objs1= [
    { name: 'Jhon', ranking: 0     },
    { name: 'Juan',    ranking: 2   },
    { name: 'Philips', ranking: 5}
];

var objs2= [
    { name: 'Erick', ranking: 4     },
    { name: 'Apollo',    ranking: 1  },
    { name: 'Mike', ranking: 3}
];

var objs3 = objs1.concat(objs2);

sort= function(){
  return objs.sort((a,b) => (a.ranking > b.ranking) ? 1 : ((b.ranking > a.ranking) ? -1 : 0));
}

average= function(){
  var sum = 0;
  for( var i = 0; i < objs3.length; i++ ){
      sum += parseInt( objs3[i].ranking, 10 );
  }

  return sum/objs3.length;
}