Set up a ratio comparing the two sets of numbers. 30 ft is to 25 mph as x is to 50 mph.
x= number of feet to stop at 50 mph
30ft/25mph= x/50mph
cross multiply
(30*50)= (25*x)
1500= 25x
divide both sides by 25
60 ft= x
ANSWER: It will take 60 ft to stop at 50 mph.
Hope this helps! :)