<PRE><B>Question 192763</B>
 let x and y be the number of 5 and 50 dollar notes respectively
:
a)x+y=16...........eq 1
  5x+50y=350.......eq 2
:
b)rewrite eq 1 to x=16-y and plug it into eq 2
:
5(16-y)+50y=350
:
80-5y+50y=350
:
45y=270
:
{{{highlight(y=6)}}} 50 dollar notes
:
x=16-y=16-6={{{highlight(10)}}} 5 dollar notes</PRE>