Question

In a cash drawer there is $125 in $5 and $10 bills. The number of $10 bills is twice the number of $5 bills. How many of each type of bill is in the drawer?

Answer 1

Let us take number of $5 bills = x and

                   number of $10 bills  = y.

Give that "number of $10 bills is twice the number of $5 bills".

So, y is twice of x,

We can setup an equation.

y= 2x                      ............................... equation(1)

Total value of all bills = $125.

We can setup another equation,

5*(number of $5 bills) + 10*(number of $10 bills) =125.

5(x) +10(y) = 125                         ................................... equation(2)

Plugging y=2x in equation(2), we get

5(x) +10(2x) = 125   .

5x+20x = 125.

Adding like terms

25x = 125

Dividing both sides by 25.

25x /25 = 125/25

x= 5.

Plugging x=5 in first equation, we get

y= 2(5) = 10.

Therefore, number of number of $5 bills=5 bills  and number of $10 bills = 10 bills.