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Kids grow up fast these days!

Algebra Level 1

Lily is twelve years old and her brother, Percy, is eight. How old will Lily be when the sum of their ages is forty?

Excel in math and science

Master concepts by solving fun, challenging problems.

It's hard to learn from lectures and videos

Learn more effectively through short, conceptual quizzes.

Our wiki is made for math and science

Master advanced concepts through explanations,
examples, and problems from the community.

Used and loved by 4 million people

Learn from a vibrant community of students and enthusiasts,
including olympiad champions, researchers, and professionals.

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by Thomas Crow

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