SOLUTION: Ina bag there 4 white balls and some red balls. If the probability of drawing the white ball from the bag is 2/5, how many red balls are there in the bag?

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Question 1083321: Ina bag there 4 white balls and some red balls. If the probability of drawing the white ball from the bag is 2/5, how many red balls are there in the bag?
Answer by ikleyn(52832)   (Show Source): You can put this solution on YOUR website!
.
Your equation is 

 = 

where "r" is an unknown number of red balls.


Simplify and solve for "r":

4*5 = 2*(4+r)  ---->  20 = 8 + 2r  ---->  2r = 20-8  ---->  2r = 12  ---->  r =  = 6.


Answer.  6 red balls.


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