Given two points of coordinates (a,b) and (A,B), the slope between them is given by:

Notice that the numerator corresponds to the change on the value of the Y-coordinates, while the denominator corresponds to the change on the value of the X-coordinate.
Substitute for (1,5) and (7,6):

Therefore, the slope of (1,5) and (7,6) is equal to 1/6.