Question
PSLE
A box contained green balls and purple balls. 40% of the balls were purple. After some black balls were added to the box, 30% of the balls were purple. What percentage of the balls in the box were black?
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PSLE
A box contained green balls and purple balls. 40% of the balls were purple. After some black balls were added to the box, 30% of the balls were purple. What percentage of the balls in the box were black?