6 bills in the deposit were $10 bills.
Step-by-step explanation:
The total number of bills he gave the teller = 24 bills
x + y = 24 ------------(1)
Let,
x be the number of $5 bills.
y be the number of $10 bills.
The total bank deposit made using $5 and $10 bills are $150.
He deposits $5 bills and $10 bills. So, the equation can be framed as :
5x + 10y = 150 --------(2)
The question is asked for how many $10 bills were in the deposit,
Here 'y' is the number of $10 bills.
To solve for y value :
The eq(1) must be multiplied by 5 and subtract eq(2) from eq(1),
5x + 5y = 120
-(5x + 10y = 150)
-5y = -30
⇒ y = 30/5
⇒ y = 6
Therefore, there were 6 bills in the deposit that are $10 bills.
