Question

Paul went on a bike ride of 30 miles. He realized that if he had gone 8 mph faster, he would have arrived 12 hours sooner. How fast did he actually ride? Paul rode _______ mph on his trip.

Answer 1

Answer: He actually rode 2 miles per hour on his trip

Step-by-step explanation: Maybe unconventional, but express the time it took, then figure the speed.

Time  = distance /speed  t will represent time, s is the speed:  t = 30/s Use the rime it would have taken at the higher speed to create an equation:

t-12 = 30/s+8   replace the y with the 30/s

30/s -12 = 30/s+8

(s)(30/s -12 ) = (s)(30/s+8 )  Cross multiply to cancel denominators  

(s-8)(30 -12s) = (s-8)(30s/s+8 ) ==> 30s +240 -12s² -96s =30s   Simplify:  

(-1)(-12s² -96s +240 ) =0 ==>  12s² +96s -240  divide all by 12

s² + 8s -20 = 0   Factor and solve for s

(s +10)(s -2) =0    s-2=0   S= 2  

Proof:

30/2 = 15 hours for original trip at 2mph,  

increase speed by 8mph   2 + 8 = 10mph

30 miles at 10mph takes 3 hours; that is 12 hours less than his actual trip.

(Brainilest, please :-)