Question
Yesterday, Neave had 910 as many black as yellow balls. He sold 21 of his yellow balls today. Now, he has thrice as many black as yellow balls. How many balls did he have altogether yesterday?
4 m

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Yesterday, Neave had 910 as many black as yellow balls. He sold 21 of his yellow balls today. Now, he has thrice as many black as yellow balls. How many balls did he have altogether yesterday?