at your age you will probably be given no more than 4 hour shifts considering you're actively going to school, 10 an hour, 4 hours a day, 5 days a week for a year is $9600, which also varies a lot so
good luck
i don't think you're going to get anywhere close to a $26,000 car on $8 an hour at the age of 15 unless you want to work at mc donald's for like 3 years