*Given
Total number of bills - 15
Total value of the bills - $47
Bills - $1 and $5
*Solution
Let:
x - number of $1 bills
y - number of $5 bills
1. The total number of bills comprising of $1 and $5 bills is 15. Thus,
x + y = 15 (EQUATION 1)
2. The total value of the bills is $47. Thus,
$1 (x) + $5 (y) = $47 (EQUATION 2)
3. There are 2 ways to solve this (system of linear equations) mathematically. You can use the elimination method or the substitution method. Using the elimination method to eliminate the variable x... (subtract Equation 1 from Equation 2)
1x + 5y = 47
_
x + y = 15
0 + 4y = 32
4. Thus, the value of y, which is the number of $5 bills is,
4y = 32
4 4
y = 8
5. The number of $1 bills (x) can then be solved using either Equations 1 or 2. Using Equation 1 to determine x,
x + y = 15
x = 15 - y
x = 15 - 8
x = 7
From the solution, we have determined that there are 8 pieces of $5 bills and 7 pieces of $1 bills.
