You have the following points at the coordinate system:
(-1, 3)
(8,-2)
In order to find the distance between the previous points, you use the following formula:
d = √( (x-x_o)² + (y-y_o)² )
By the given cordinates you can take:
x = 8, x_o = -1
y = -2, y_o = 3
By replacing in the formula for the distance you have:
d = √( (8 - (-1))² + (-2 - 3)² )
d = √( (8+1)² + (-5)² )
d = √( 81 + 25 )
d = √(106) ≈ 10.29 ≈ 10.3
Hence, the distance between the points is approximately 10.3