I believe the correct form of the given equation is:
  
 I = square root (W / R) ---> where both W and R is inside the square root symbol
  
 where,
 I = the current
 W = the electric power
 R = resistance in ohms
  
 Now to solve for the value of I for each set, simply substitute the values of W and R into the equation, that is:
  
 when W=100,R=25
 I = square root (100 / 25)
 I = square root (4)
 I = 2
  
 when W=100,R=50
 I = square root (100 / 50)
 I = square root (2)
 I = 1.414