Posted by Lizzy on .
The time it takes Javier to go to school and his walking rate are inversely proportional. If it takes him 12 mins walking at 3 mph how long does it take if he walks at 4 mph?

Math 
Steve,
t = k/r
12 = k/3
k = 36
t = 36/r
when r=4,
t=36/4 = 9 min