Question 1207588
y of the twenty-dollar bills
48-y of the ten-dollar bills


{{{10(48-y)+20y=880}}}----account for the money

{{{10*48-10y+20y=880}}}

{{{(20-10)y=880-10*48}}}

{{{(2-1)y=88-48}}}

{{{highlight(y=40)}}}------------so then 8 of the ten-dollar bills;
40 of the twenty-dollar bills.