text: const subtract = (x, y) => { return x - y }
  
  const subtracter = new Vue({
    el: '#subtracter',
    data: {
      first: 10,
      second: 5
    },
    computed: {
      difference: function () {
        const i = parseInt(this.first)
        const j = parseInt(this.second)
        return `The difference is ${subtract(i, j)}.`
      }
    }
  })