Question 1016501
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x=red balls to add
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{{{x/(6+7+5+x)=6/7}}}
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{{{x/(18+x)=6/7}}} Cross multiply.
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{{{7x=6(x+18)}}}
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{{{7x=6x+108}}}
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{{{x=108}}}
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ANSWER: Add 108 red balls.
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