Answer by greenestamps(13203)   (Show Source): You can put this solution on YOUR website!
 


Given the ratio of 8:9 of girls to boys, one common way to start working the problem is to let the number of girls be 8x and the number of boys be 9x.


Then, given that the total number of students is 340,









ANSWER: The number of boys is 9x = 9(20) = 180.


 

Answer by ikleyn(52810)   (Show Source): You can put this solution on YOUR website!
 .





            @greenestamps just showed you one good way to start and to solve the problem.





            Another way is THIS







Let x be the number of boys.

Then the number of girls is  (340-x), and you can write the proportion


     = .


From the proportion,

    9*(340-x) = 8x

    9*340 = 8x + 9x

    9*340 = 17x


Next divide both sides by 17

    9*20 = x

    x = 180   boys.    ANSWER




Solved.





 

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