1. Luis made a $150 bank deposit using $5 bills and $10 bills. He gave the teller a total of 24 bills. How many $10 bills were in the deposit?

6 $10 bills

Step-by-step explanation:

First you have to make a system of equations like such

5x + 10y = 150

x + y = 24

Now you can use any strategy to simplify it but I'll use multiplication and the subtraction:

5x + 10y = 150 - 5x + 5y = 120 = 5y = 30 this simplified is y = 6. You then substitute 6 for y in either equation. x + 6 = 24 and make it on opposite sides. x = 18.

So 18 $5 bills and 6 $10 bills