title: Grade calculation in shell script
body: <p>I got a file name <code>txtGrade.txt</code> contain with this:</p>
  
  <pre><code>Name               Score
  Nicki Minaj        60
  </code></pre>
  
  <p>I want to read and calculate every person in file by shell script and answer the grade like:</p>
  
  <pre><code>Name                Score         Grade
  Nicki Minaj         60                C
  </code></pre>
  
  <p>The condition is <code>A&gt;=80 , 79&gt;=B&gt;=70 ,69&gt;=C&gt;=60 , 59&gt;=D&gt;=50 , 49&gt;=F</code></p>
  
  <p>Thank you for helping me 
  Appreciate. </p>