Question

hat is the slope of the line that passes through (3, –7) and (–1, 1)

Answer 1

The slope of any line through two points (X1, Y1) and (X2, Y2) is calculated as follows:
Subtract the two Xs,
Subtract the two Ys
Slope = Y-result / X-result.

In your case:
X-result = 3 - (-1) = 4
Y-result = -7 - 1 = -8
Slope = Y-result / X-result = -1 / 4 = -2