a bank teller has 54 in $5 and $20 bill s. the total value is $780. how many 5 dollars are there

34

X+y=54

5x+20y=780

-5(x+y=54)

-5x-5y=-270
5x+20y=780

15y=510
Y=34
X=20

5(20)+20(34)=780
Five dollars bills = 20

X+y=54

5x+20y=510

To find the number of $5 bills, we can set up a system of equations based on the given information.

Let's say the number of $5 bills is "x". Since the teller has a total of 54 bills, we can determine the number of $20 bills by subtracting "x" from 54.

So, the number of $20 bills is 54 - x.

Now, let's calculate the total value of the $5 bills:
Value of $5 bills = number of $5 bills * $5 = x * $5 = 5x

Similarly, let's calculate the total value of the $20 bills:
Value of $20 bills = number of $20 bills * $20 = (54 - x) * $20 = 20(54 - x) = 1080 - 20x

We are given that the total value of the bills is $780. So we can set up the equation:

Total value = Value of $5 bills + Value of $20 bills
$780 = 5x + (1080 - 20x)

Simplifying the equation:
$780 = 5x + 1080 - 20x

Combining like terms:
$780 = -15x + 1080

Now, let's solve for x.

Subtracting 1080 from both sides:
$780 - $1080 = -15x + $1080 - $1080
-$300 = -15x

Dividing both sides by -15:
-$300/-15 = -15x/-15
20 = x

Therefore, there are 20 $5 bills.