The band is selling wrapping paper for a fundraiser. Customers can buy rolls of plain wrapping paper and rolls of shiny wrapping paper. The band sold a total of 55 rolls and made $950. If a roll of plain wrapping paper cost $14 and a roll of shiny cost $20, how many rolls of each did they sell ?

x= # plain rolls
y= # shiny rolls

QUANTITY EQUATION:
x+y=55

COST EQUATION:
$14x + $20y= $950

SOLVE:
Solve for one variable in quantity equation. Substitute that answer in cost equation.

STEP 1:
x+y=55
subtract y from both sides
x= 55-y

STEP 2:
$14x + $20y= $950
14(55-y) + 20y= 950

multiply 14 by all in parentheses
(14*55)+(14*-y) + 20y= 950
770-14y+20y= 950

combine like terms
770+6y= 950

subtract 770 from both sides
6y= 180

divide both sides by 6
y= 30 shiny rolls

STEP 3:
Substitute y answer in either equation to solve for x.

x+y=55
x+30=55
subtract 30 from both sides
x= 25 plain rolls

Hope this helps! :)