Question 1206818
<pre>
PERSON       VARIABLE        STEP 1          STEP 2
Sally           x             x-3x/7           4x/7
Andrew          y             y-36            y-36+20=y-16
</pre>
After step 2, description gave
{{{y-16=(1/4)(4x/7)}}}
{{{7y-112=x}}}


Described initial total for both combined,  $320.
{{{x+y=320}}}


The system, {{{system(x=7y-112,x+y=320)}}}


Simple substitution,.....
{{{system(x=266,and,y=54)}}}
-but the question was,
"How much did Sally have left?"

-

{{{(4/7)266=highlight(152)}}}-----------how much she had left