Andrew M. answered 02/28/20
Experienced Math Tutor and Engineer Specializing in Upper Level Math
The distance formula is
d = √[(x2 - x1)2 + (y2 - y1)2]
Where your two points are (x1, y1) & (x2, y2), in this case though, we see that both y values are the same so when we subtract them
-8 - (-8) = 0
So for this problem we are really only concerned with the distance between the two x values as this is a horizontal line. We can see that the distance from -5 to the origin is 5 and the distance from the origin to 10 is 10 so the distance is the sum of those two numbers which is 15.
For the sake of using the distance formula though, you would get:
d = √[10 - (-5)]2 = √(15)2
the square and the square root cancel leaving you with d = 15