A × B means 'A is the wife of B';

A ÷ B means 'A is the father of B';

Which of the following expression means 'R' is the paternal grandfather of 'S'?

R ÷ J ÷ S × U

After checking all the options, we get the answer from option (iii):

*********************************************************

Please note:

  l   ⇒ Vertical line shown "generation gap".

 =  ⇒ Double lines shown "relation of spouse" 

—  ⇒ Horizontal line shown "relation in same generation other than spouse".

     ⇒ Rectangular box shown " Male".

     ⇒ Circular box shown " Female".

*********************************************************