Thomas wants to rent a lawn mower. He has to pay a fixed base cost plus a daily rate for renting the lawn mower. The table shows the amount of money, y, in dollars, that Thomas has to pay for renting the lawn mower for x days: Lawn Mower Rental Number of days(x) Rent (dollars)(y) (x) (y) 0 12 1 21 2 30 3 39 4 48 Which equation best shows the relationship between x and y? y = x + 21 y = 9x + 21 y = 9x + 12 y = x + 12