To earn money, Alex started a lawn-mowing business in his neighborhood. Alex bought a lawn mower for $200, and the average cost for gasoline to mow each lawn in his neighborhood is $0.50. He charges $22.00 for each lawn he mows in his neighborhood. When Alex mows lawns in his neighborhood, the total cost, , can be expressed by
C=200+.50n, and the total amount of money he charges, , can be expressed by R=22n.
Alex wants to buy a basketball goal for $400. How many lawns will he need to mow?