Question 879125
<pre>
(Average of m and n) = {{{(m+n)/2}}}

{{{48m+48n}}}{{{""=""}}}{{{2880}}}

{{{48(m+n)}}}{{{""=""}}}{{{2880}}}

Divide both sides by 48

{{{48(m+n)/48}}}{{{""=""}}}{{{2880/48}}}

{{{m+n}}}{{{""=""}}}{{{60}}}

(Average of m and n) = {{{(m+n)/2}}}

Substitute 60 for m+n in {{{(m+n)/2}}} = {{{60/2}}} = 30

Edwin</pre>