Question 67215

Let x=his speed to school
Then 2x=his speed back

We are told that the total trip (to & back) is 48 mi

We are also told that the time to school plus the time back equals 9 hours

We'll use the formula: distance(d) =rate(r) times time (t) or d=rt and
t=d/r

time to school:  24/x

time from school: 24/2x

Our equation to solve is
24/x+24/(2x)=9  multiply through by x
24(x/x)+24(x/2x)=9x simplifying
24+12=9x

9x=36
x=4 miles per hour ---------speed to school
time to school:  24/x=24/4=6 hours-----------time to school

2x=2*4=8 miles per hour---------------rate from school
time from school: 24/2x=24/8=3 hours ----time from school

CK

6 hours + 3 hours = 9 hours

8 miles per hour = 2 times 4 miles per hour


Hope this helps ----ptaylor