The thing with collinear points is that they all lie on the same line. The question mentions that AB=BC which means that Point B must be the midpoint of Point A and Point C. Therefore, in order to find the the coordinates of Point C you would basically have to use the mid-point formula.
The X coordinate of Point C: (x+4) / 2 =1. If you multiply both sides by 2 you get:
x+4 = 2 and then by taking the 4 to the other side you get x=-2.
The Y coordinate of Point C: (y+5) / 2 = -1. The same process you used to find the x coordinate will also be applied here. Therefore: y+5= -2.
y= -7
And therefore the coordinates of Point C are: (-2,-7).
Hopefully that helped =)
The X coordinate of Point C: (x+4) / 2 =1. If you multiply both sides by 2 you get:
x+4 = 2 and then by taking the 4 to the other side you get x=-2.
The Y coordinate of Point C: (y+5) / 2 = -1. The same process you used to find the x coordinate will also be applied here. Therefore: y+5= -2.
y= -7
And therefore the coordinates of Point C are: (-2,-7).
Hopefully that helped =)