Question 834220
She has a total of $880 in five dollar bills and 20 dollar bills.
she has four more twenties than fives.
how many 20 dollar bills does she have.


let x = number of 5 dollar bills and y = number of 20 dollar bills.


5x + 20y = 880 is your first equation.


this equation is the equation that counts up the total money based on the different bills that she has.


y = x + 4 is your second equation.


this equation give you the relationship between the number of five dollar bills she has and the number of 20 dollar bills that she has.


you have 2 equations that need to be solved simultaneously.


they are:


5x + 20y = 880
y = x + 4


substitute y = x + 4 for y in the first equation to get:


5x + 20(x + 4) = 880


solve for x in this equation.


start with:
5x + 20(x+4) = 880
simplify to get:
5x + 20x + 80 = 880
combine like terms to get:
25x + 80 = 880
subtract 80 from both sides of this equation to get:
25x = 800
divide both sides of this equation by 25 to get:
x = 800 / 25 = 32


x is the number of 5 dollar bills.
since y = x + 4, then y = 36 = the number of 20 dollar bills.


so x = 32 and y = 36


she has 32 five dollar bills and 36 twenty dollar bills.


32 * 5 = 160 dollars
36 * 20 = 720 dollars
720 + 160 = 880 dollars


numbers check out and the solution is good.


she has 32 five dollar bills and 36 twenty dollar bills.