Answer:
The more money needed to purchase a bike = $ 142.5
Step-by-step explanation:
Money earned for each driveway = $ 7.5
Money earned in three driveways = 7.5 × 3 = $ 22.5
Money earned in 7 days = 22.5 × 7 = $ 157.5
The price of new bike = $ 300
More money needed to purchase a bike = $ 300 - $ 157.5
More money needed to purchase a bike = $ 142.5
Therefore the more money needed to purchase a bike = $ 142.5
