To answer this question, we can set up a system of equations. Let's call the number of ten-dollar bills "x" and the number of five-dollar bills "y."
From the problem, we know two things:
1. "It contains 4 times as many five-dollar bills as ten-dollar bills," which can be written as: y = 4x.
2. "The total amount of money in the cash register is 1050 dollars," which can be written as: 10x + 5y = 1050.
We can use these equations to solve for the number of ten-dollar bills. Let's substitute y = 4x into the second equation:
10x + 5(4x) = 1050
10x + 20x = 1050
30x = 1050
x = 1050 / 30
x = 35
Therefore, there are 35 ten-dollar bills in the cash register.