If it takes your car 30 ft to stop when travelling at 25 mph, it will take your car to stop when travelling at 50 mph.

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! :)