title: Why is the sum of bytes integer?
body: <p>I have tyo byte variable</p>
  
  <pre><code>byte a = 3;
  byte b = 4;
  </code></pre>
  
  <p>If I sum them, the value of sum is integer.</p>
  
  <pre><code>byte z = a+b  //error, left side is byte, right side is integer
  </code></pre>
  
  <p>Why a+b is int?</p>