When Mr. Crain was driving to work in the morning, there was heavy traffic, so he was traveling at a speed of 25 mph. When he was coming back after work there where no traffic, so he drove at a speed of 45 mph. Find the distance from Mr. Crain's home to his office, if it took him 20 more minutes to get to work than to drive home.

let the distance from home to work be x;
time=distance/speed
Time taken to travel to work is:
time=x/25
Time taken to reach home from work:
time=x/45
given that it took him 20 min more to travel to work than going home we shall have:
x/25-x/45=20/60
solving for x we get:
x=75/4=18.75 miles