In reducing ones speed from 70mph to 50 mph how much of a percentage decrease in stopping distance is realized

28.57142857% decrease

Step-by-step explanation:

To find the percentage decrease in speed, take the original speed minus the new speed over the original speed. Then multiply by 100%

original speed = 70 new speed = 50

percent decrease = (70-50) / 70 * 100%

= 20/70 * 100%

=28.57142857%