Answer:
x = -4 , 4 
Explanation:
The point (x,4) is equidistant from (0,1) and line y=-1 
y=-1, it is horizontal line. 
Let point on line be (x,-1)
Distance formula: 

Distance between (x,4) and (x,-1) = Distance between (x,4) and (0,1) 






hence, the value of x is 4 and -4