Question 1084644
5/7 of a group of students are girls .if the no.of girls is 18 more than the no.of boys .how many students are there altogether
<pre>
Let the number of students = {{{n}}}
</pre>
5/7 of a group of students are girls .
<pre>
That means that 5 sevenths are are girls and
the remaining 2 sevenths are boys 

So the number of girls = 5/7ths of n, or {{{expr(5/7)n}}} 

And the number of boys = 2/7ths of n, or {{{expr(2/7)n}}}
</pre>
the no.of girls is 18 more than the no.of boys .
<pre>
{{{expr(5/7)n}}} {{{""=""}}} {{{expr(2/7)n}}}{{{""+""}}}{{{18}}}

Multiply every term by 7

{{{5n}}} {{{""=""}}} {{{2n}}}{{{""+""}}}{{{126}}}

{{{3n}}} {{{""=""}}} {{{126}}}

{{{n}}} {{{""=""}}} {{{42}}}

Edwin</pre>