Question
PSLE
A box contained yellow marbles and black marbles. 60% of the marbles were black. After some white marbles were added to the box, 21% of the marbles were black. What percentage of the marbles in the box were white?
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PSLE
A box contained yellow marbles and black marbles. 60% of the marbles were black. After some white marbles were added to the box, 21% of the marbles were black. What percentage of the marbles in the box were white?