SOLUTION: Xavier drove from his house to the country in 3 hours. Driving at a speed of 12 mph less than on the trip out, he spent 4 hours on the return trip. What was his average rate on t

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Xavier drove from his house to the country in 3 hours. Driving at a speed of 12 mph less than on the trip out, he spent 4 hours on the return trip. What was his average rate on t      Log On


   

Question 1002843: Xavier drove from his house to the country in 3 hours. Driving at a speed of 12 mph less than on the trip out, he spent 4 hours on the return trip. What was his average rate on the return trip?
Answer by josgarithmetic(39625) About Me  (Show Source):
You can put this solution on YOUR website!
             rate       time     distance
GOING          r         3        d
RETURN        r-12       4        d

The question asks for the rate for the RETURN trip. The variables can be
reassigned this way: 
             rate       time     distance
GOING         r+12       3        d
RETURN        r          4        d

The new assigning for the rates still keeps the return rate as 12 mph less than the going-to rate.
system%283r%2B36=d%2C4r=d%29

3r%2B36=4r
highlight%28r=36%29