Which one is it I don’t know

Solve the system of equations. y= 2x y= x^2 - 15

What’s the domain of this function? fastttt

Janie has $3. she earns $1.20 for each chore she does and can do fractions of chores. she wants to earn enough money to buy a cd for $13.50. write an inequality to determine the number of chores, c, janie could do to have enough money to buy the cd.