Question 293277
The sum of two numbers is less than or equal to 18. The second number is 8 less than the first. What are the possible values for the first of the two numbers? 
<pre><font size = 5 color = "indigo"><b>
Let F = first nuumber
Let S = second number

Then
{{{system(F + S <=18,
S = F - 8)}}}

Substitute {{{(F-8)}}} for S in {{{F+S<=18}}}

{{{F+"[(F-8)-S)]"<=18}}}
{{{F+F-8<=18}}}
{{{2F-8<=18}}}
{{{2F<=26}}}
{{{F<=13}}}

The first number is less than or equal to 13.

Edwin</pre>