Question 1151163
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            @greenestamps just showed you one good way to start and to solve the problem.


            Another way is THIS



<pre>
Let x be the number of boys.

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


    {{{(340-x)/x}}} = {{{8/9}}}.


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.    <U>ANSWER</U>
</pre>

Solved.