Question
PSLE
A box contained gold marbles and purple marbles. 40% of the marbles were purple. After some black marbles were added to the box, 36% of the marbles were purple. What percentage of the marbles in the box were black?
2 m

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PSLE
A box contained gold marbles and purple marbles. 40% of the marbles were purple. After some black marbles were added to the box, 36% of the marbles were purple. What percentage of the marbles in the box were black?