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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?

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Excel in math and science

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It's hard to learn from lectures and videos

Learn more effectively through short, interactive explorations.

Used and loved by over 6 million people

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including olympiad champions, researchers, and professionals.

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by Thomas Crow

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