SOLUTION: There are 4 black and 4 white marbles in a box. How many white marbles would you take out of the box so that 2/3 of the remaining marbles would be black?

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Question 554069: There are 4 black and 4 white marbles in a box. How many white marbles would you take out of the box so that 2/3 of the remaining marbles would be black?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = number of white marbles to be removed
given:
2/3 of the remaining marbles are black
That means 1/3 must be white
+%284+-+x%29+%2F+%288+-+x%29+=+1%2F3+
+4+-+x+=+%281%2F3%29%2A%28+8+-+x+%29+
+3%2A%28+4+-+x+%29+=+8+-+x+
+12+-+3x+=+8+-+x+
+-2x+=+-4+
+x+=+2+
If you remove 2 white marbles, then the
black ones are 4/( 4 + 2 ) = 2/3 of the
remaining marbles