Answer:
Given in quesion:Point B (3,1) and point A is -1. Distance between A and B is 5 units.
Using distance formula for AB we obtain,
AB^2=(x2-x1)^2 + (y2-y1)^2
5^2=(3+1)^2 + (1-y)^2
25-16=(1-y)^2
9=(1-y)^2
1-y=3
y= -2
Therefore the possible co-ordinates of A are(-1,-2).This is your required answer.