There are 7 days in a week, so if he doesn't go to work for 3 days, he goes 7-3 = <<7-3=4>>4 days every week
He travels 140km each day for a weekly total of 140*4 = <<140*4=560>>560km
In 4 weeks he will travel a total of 4*560 = <<4*560=2240>>2240km
#### 2240