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AGE Problem ( not actually )

Level pending

WHEN I WAS 10 YEARS OLD, MY SISTER'S AGE WAS HALF OF MINE. I GROW UP AND NOW I AM 50 YEARS OLD, WHAT WOULD BE MY SISTER'S AGE?

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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, interactive explorations.

Used and loved by over 5 million people

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

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by Elton Jay Pasco

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