Question
Billy has some blue and brown balls. The total mass of all his balls is 235 g. He has 10 less blue balls than brown balls. The average mass of the blue balls is 4 g. The average mass of the brown balls is 7 g. How many balls does Billy have altogether?
3 m

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Billy has some blue and brown balls. The total mass of all his balls is 235 g. He has 10 less blue balls than brown balls. The average mass of the blue balls is 4 g. The average mass of the brown balls is 7 g. How many balls does Billy have altogether?