There are 50 marbles in a box which has a mixture of white, red and blue marbles. There were originally 20 white marbles and an equal number of red and blue marbles. Jack removes a number of marbles equal to double the difference between the number of white marbles and the number of blue marbles. How many marbles are left in the box?
How many red and blue marbles are there? ** 20 of 50 marbles are white so there are 50-20 = 30 red and blue marbles
How many red and blue marbles are there? ** The number of red marbles and blue marbles is the same, so there are 30/2 = <<30/2=15>>15 of each color
How many marbles are there between white and blue? ** The difference between the number of white marbles and blue marbles is 20-15 = <<20-15=5>>5
How many marbles are removed? ** Double the difference is 5*2 = <<5*2=10>>10 marbles
How many marbles are left in the box? ** 10 marbles are removed to leave 50-10 = <<50-10=40>>40 marbles
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