The formula for slope is:
slope=y2-y1/x2-x1 where (x1,y1) and (x2,y2) are points on the line
In this situation we know the x values of two points, and we know the slope, so we can solve for the missing y values.
slope=-7
(11,y1) (16,y2)
Now lets plug in the information into the formula.
slope=y2-y1/x2-x1
-7=y2-y1/16-11
-7=y2-y1/5
multiply both sides by 5
-35ft=y2-y1
distances cannot be negative so lets change -35ft to a positive number
35ft=y2-y1
The vertical distance between the two points is 35feet
Answer= A) 35ft