math
posted by jean .
John's father works in Franklin. It is 39 miles from Franklin to his home. If he leaves work at 7:20 P.M.and travels an average speed of 43 m/hr., at what time will he get home?
Please explain.

Distance = rate * time
39 miles is the "Distance" from Franklin to his home, and 43 m/hr is his "rate" of travel. You are trying to figure out the "time" it takes for him to get home traveling at this "Distance" and "rate".
Switch the Distance formula around for "time" and plug the numbers in:
time = Distance/rate
time = 39 miles/43 mph
time = .09 hours 
Woops. I accidentally wrote .09 instead of .907
However, the actual answer is just the result of the distance divided by the rate (aka whatever 39/43 is).