Question 1184033
<pre>
NUMBERS         DESCRIPTION
x                 x
y                 x-2
z
SUM               15
</pre>

{{{x+(x-2)=2z}}}

-

{{{2x-2=2z}}}

{{{x-1=z}}}

<pre>
Revising the table,
NUMBERS         DESCRIPTION
x                 x
y                 x-2
z                 x-1
SUM               15
</pre>


{{{highlight_green(x+(x-2)+(x-1)=15)}}}

.

.
{{{highlight(x=6)}}}, and then,...