const app = new Vue({

  el: '#app',

  data: {

    persons: [

    {Name: 'Ali', Family: 'Bahaari', Age: 20, Count: 0, price: 200},

    {Name: 'Akbar', Family: 'Jahan', Age: 30, Count: 0, price: 2500},

    {Name: 'Amir', Family: 'Pirozi', Age: 40, Count: 0, price: 500},

    {Name: 'Reza', Family: 'Khosravi', Age: 50, Count: 0, price: 100}

    ]

  },

  computed: {

     total() {

       let total = 0

       this.persons.forEach(person => total += person.price )

       return total

     }

  }

})