Jackson has saved $174.
He wants to purchase an electric dirt bike that costs $459.
If he saves $15 each week from the money he earns doing yard work and another $4 each week from his allowance, how many weeks will it take Jackson to save enough money to buy the bike?
Each week, Jackson saves a total of $15 + $4 = $<<15+4=19>>19.
To save enough money to buy the bike, it will take him $459 ÷ $19 = <<459/19=24.157894736842106>>24.157894736842106 weeks.
Therefore, it will take him 25 weeks to save enough money to buy the bike. Answer: \boxed{25}.