He does the long drive 7-4=<<7-4=3>>3 days a week
So he drives a total of 4*50+3*100=<<4*50+3*100=500>>500 miles a week
That means the car cost 500*.1=$<<500*.1=50>>50 just for the mileage per week
So he pays 100+50=$<<100+50=150>>150 per week for the car
That means the total cost of the car is 150*52=$<<150*52=7800>>7800 a year
#### 7800