Question 537767
<pre>
{{{y/4}}} + {{{3y/5}}}

The smallest denominator which  4 and 5 will both divide evenly into is 20.

The 4 on the bottom of the first term needs to be multiplied by 5 so that
it will become 20. So we multiply the first fraction by {{{red(5/5)}}}.

The 5 on the bottom of the second term needs to be multiplied by 4 so that
it will become 20. So we multiply the second fraction by {{{red(4/4)}}}.

{{{red(5/5)*""}}}{{{y/4}}} + {{{red(4/4)*""}}}{{{3y/5}}}

{{{5y/20}}} + {{{12y/20}}}

{{{17y/20}}}

Edwin</pre>