Question 979948
Try to analyze the problem and assign variables to any quantity which is not known.  The question is, how much money does he save each week?


$6.25/hour job;
$7.50/hour job;
40 hours/week total work time;
Save 18% of gross wages;


x, hours at lower paid job.
y, hours at better paid job.
{{{x+y=40}}}
.
{{{6.25*x+7.5*y}}}, the weekly wages.
{{{highlight_green((18/100)(6.25x+7.5y))}}}, Amount Saved Each Week.  This is what is asked to find or evaluate.  


That should help.


You do not need to be given both x and y;
only x  OR  y needs to be known or given.