A man drove to work at an average rate of speed 60 miles per hour and

returned over thesame route driving at an average rate of speed of 40 miles per hour. If his total driving time was 1 hour, what was the total number of miles in

the round trip?

let x = miles

we have x miles / 60mph plus x miles / 40 mph = 1 hour

x/60 + x/40 = 1

we need to calculate 2x for the round trip

calculate common denominator and rewrite the 2 fractions:

2x/120 + 3x/120 = 1

5x = 120

x = 120/5 = 24 miles

24*2 = 48 miles total

check:

1 way would be 48/2 = 24 miles

24/60 = 0.4 hours to drive 24 miles at 60 mph

24/40 = 0.6 hours to drive 24 miles at 40 mph

0.6 + 0.4 = 1 hour