May you write me a simple application in Vue 3 where there is a number and two buttons that increment and decrement that number?
Of course, below is an example of a bare-bones Vue application that has a number and two buttons that increment and decrement that number using inline event handling....

<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Learning Vue</title>
  <script src="https://unpkg.com/vue@3.0.0"></script>
</head>
<body>

  <div id="app">
    <p>{{ num }} years old</p>
    
    <button v-on:click="num++">Increase age</button>
    <button @click="num--">Decrease age</button>
  </div>


  <script src="app.js"></script>
</body>
</html>

With the accompanying Javascript file looking like this ...

const app = Vue.createApp({
  data() {
    return {
      num: 45
    }
  }
})

app.mount('#app')