Step-by-step explanation:
do you want to know why this is the right answer ?
first of all, points don't have slopes. but a line connecting these 2 points does.
so, whoever phrased that question showed a remarkable inability of percussion precise language necessary for successful math. and a shame for a math teacher.
so, now back to the why.
the slope of a line is the ratio y/x indicating how many units y changes, when x changes a certain amount of units when going from one point to another.
going from (2, 4) to (1, 7)
x changes by -1 (from 2 to 1),
y changes by +3 (from 4 to 7).
so, the slope of the line connecting these two points is
3/-1 = -3
