Slope = change in y ÷ change in x = (1 − 4) ÷ (1 − -1) = -3 ÷ 2 = -3/2. Here, slope tells how much y changes for each 1-unit change in x. A negative slope means the line goes downward from left to right, while a positive slope means it goes upward. Always subtract the coordinates in the same order for y and x so the sign of the slope stays correct. The correct answer is -3/2, which matches the calculation or reasoning shown.