<PRE><B>Question 339003</B>
plastic cups for $3.25 each : let the numberof cups be x
and ceramic cups for $4.50 each : this will be 500-x cups
500 cups were sold for a total of $2,090,
..
3.25x+4.5(500-x)=2090
3.25x+2250-4.5x= 2090
-1.25x=2090-2250
-1.25x=-160
divide by -1.25
x=-160/-1.25
x= 128 plastic cups.
remaining will be ceramic cups 
500-128=372 </PRE>