Distance between (–1, 2) and (–5, 2)?

In mathematics, slope (designated by the letter 'm') is defined as the ratio of the 'Y' axis to the 'X' axis between 2 points. In less formal terms this is called the "rise over the run".
The formula for determining the slope between 2 points is:
Slope = m = (Y2 -Y1) ÷ (X2 -X1)In the above graph we have 2 points where 'a' has the values of x=1 y=2 and the values of point 'b' are x=5 y=4. The math "shorthand" for this is a(1,2) and b(5,4).
Using the formula, we can determine a linear equation's slope from these 2 points.
m = (4 - 2) ÷ (5 - 1)m = 2 / 4m = .5

The exact distance is  7.615773105863909

Graph a should be your answer