Question 1181834
The smaller of two numbers is thrice the larger.<pre> 
{{{(matrix(2,1,The,Smaller))}}}{{{""=""}}}{{{3*(matrix(2,1,The,Larger))}}}
</pre>The larger number is eight more than the smaller one.<pre>
{{{
(matrix(2,1,The,Larger))}}}{{{""=""}}}{{{(matrix(2,1,The,Smaller))}}}{{{""+""}}}{{{8}}}

Put S for the Smaller.
Put L for the Larger.

{{{matrix(1,1,S)}}}{{{""=""}}}{{{3*matrix(1,1,L)}}}

{{{matrix(1,1,L)}}}{{{""=""}}}{{{matrix(1,1,S)}}}{{{""+""}}}{{{8}}}

Substitute {{{3*matrix(1,1,L)}}} for S in the second equation:

{{{matrix(1,1,L)}}}{{{""=""}}}{{{matrix(1,1,3*L)}}}{{{""+""}}}{{{8}}} 

Subtract {{{3*L}}} from both sides:

{{{L-3*L}}}{{{""=""}}}{{{8}}}

{{{1*L-3*L}}}{{{""=""}}}{{{8}}}

{{{-2*L}}}{{{""=""}}}{{{8}}}

Divide both sides by -2

{{{(-2*L)/(-2)}}{{{""=""}}}{{{8/(-2)}}}

{{{(cross(-2)*L)/(cross(-2))}}}{{{""=""}}}{{{-4)}}}

{{{L}}}{{{""=""}}}{{{-4}}}

Edwin</pre>