Bob drove from home to work at 60mph. after work the traffic was heavier, and he drove home at 25mph. his driving time to and from work was 1 hour and 8 minutes. how far does he live from his job

Let's call the distance between Bob's house and his job " Q miles".

When he drives the distance at 60 mph, it takes him ( Q/60 ) hours to cover it.

When he drives the distance at 25 mph, it takes him ( Q/25 ) hours to cover it.

When he drives both ways, it takes him ( 1hr 8min ) total driving time.

1hr 8min = 68 minutes.  That's 68/60 hours.

(Q/60 hr) + (Q/25 hr) = 68/60 hr

Q/60 + Q/25 = 68/60

Multiply each  side by 60:

Q + 60Q/25 = 68

Now multiply each side by 25:

25Q + 60Q = 1700

85Q = 1700

Divide each side by 85 :  Q = 20 miles

Check:

Driving 20 miles at 60 mph takes 1/3 hour = 20 minutes

Driving 20 miles at 25 mph takes 4/5 hour = 48 minutes

Driving both ways takes (20min + 48 min) = 68 minutes   yay!

³33333333333333333333