Question 1043055
<pre>After paying "1/m"th and "1/n"th of a bill, "a" remained due. 
Determine the bill amount. 

My attempt:

Let x = amount of bill.

x - 1/m - 1/n = a       <b><-- NO! Should be</b> {{{x-expr(1/m)*x-expr(1/n)*x = a}}}

lcd = mn                <b><-- yes but multiply through by it, because 
                               the idea is to CLEAR of fractions.  Get
                               rid of them.  Don't keep them!</b>   

xmn - 1/mn - 1/nm = amn  <b><--No! Should be {{{mnx-nx-mx = amn}}}
                               which has <u>NO</u> fractions!</b>

How do I continue ?   

<b>From this:

{{{mnx-nx-mx = amn}}}

factor out x on the left:  

{{{x(mn-n-m) = amn}}}

Divide both sides by what's in the parentheses

{{{x = amn/(mn-n-m)}}}

Note: The tutor below failed to correct your error.</b>

Edwin</pre></b>