SOLUTION: Box A has 9 green balls and 4 red balls. Box B has 12 green balls and 5 red balls. Suppose you want the fraction of green balls in box A to equal the fraction of red balls in box

Question 274427: Box A has 9 green balls and 4 red balls. Box B has 12 green balls and 5 red balls. Suppose you want the fraction of green balls in box A to equal the fraction of red balls in box B. How many green balls must you move from Box A to Box B?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Box A has 9 green balls and 4 red balls.
Box B has 12 green balls and 5 red balls.
Suppose you want the fraction of green balls in box A to equal the fraction of red balls in box B.
How many green balls must you move from Box A to Box B?
:
Let x = no. of green balls moved
:

:
= ; (relationship is reversed)
;
Cross multiply
(9-x)(12+x) = 4 * 5
FOIL
108 + 9x - 12x - x^2 = 20
;
Arrange as a quadratic dquation
-x^2 - 3x + 108 - 20 = 0
-x^2 - 3x + 88 = 0
Multiply by -1
x^2 + 3x - 88 = 0
Factor
(x+11)(x-8) = 0
positive solution
x = 8 balls are moved
:
:
See if that is true
= which is: =
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