At 15, you will finish AoPS Prealgebra quickly, then attack Introduction to Algebra while studying Introduction to Geometry concurrently. Daily discipline: Alcumus practice and aligned free videos reinforce concepts and problem-solving. Master arithmetic, number theory, proofs in Prealgebra; conquer linear, quadratic, functions in Algebra; and prove theorems in Geometry. Expect hard problems, full solutions, and weekly timed sets. No excuses: two hours daily, targeted reviews, and relentless problem practice until mastery with tutor check-ins weekly.