The value of "r" is -3 so the line passes through (r,-2) and (-7,-1) has a slope of m = -1/4
Solution:
Given that line passes through (r, -2) and (-7, -1) has a slope of

To find: value of r
The slope of line passing through two points
and
is given as:

Here given that slope


Substituting the values in above formula, we get


Thus the value of "r" is -3