On Saturdays, Jason mows yards and washes cars. He charges $25 per yard and an additional cost for each car he washes. Last Saturday, Jason mowed 5 yards and washed 10 cars. He made a total of $225, and the equation `5(25)+10x=225` describes the amount of money he made that Saturday. What does the variable `x` represent in this situation?
The number of yards Jason mowed
The number of cars Jason washed
The amount Jason charged for each yard mowed.
The amount Jason charged for each car washed.