SOLUTION: I'm having trouble with this problem 30% of the seventh-graders and 40% of the eighth-graders went to the school dance. At the dance, the ratio of seventh to eighth graders was

Question 1099986: I'm having trouble with this problem
30% of the seventh-graders and 40% of the eighth-graders went to the school dance. At the dance, the ratio of seventh to eighth graders was 21:32. What is the ratio of seventh to eighth graders that did not go to the dance?
Thank you.
Answer by ikleyn(52835) (Show Source): You can put this solution on YOUR website!
.

Let s = the number of the school seventh-graders and 
    e = the number of the school eight-graders.


We are given 


 = ,   or, equivalently,

 = ,

which implies 

 =  = .



The problem asks about  .   This ratio is 


 =  =  =  =  =  = .



Answer.  The ratio under the question is  .

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