You can find 15 DVDs.
165 divided by 11 = 15
(# of five dollar bills=f ; # of ten dollar bills=t)
3t-1=f ⇒ this means that if there were 1 $5 bills, there would be 2 $10 bills.
So the ratio of $5 bills to $10 bills is 1 to 2.
We can plug that into another equation:
f+t=410 ⇒ I havent actually learned this in school yet so I just made a chart: $10 ║ $5
------║------
2 ║ 1 = $25
4 ║ 2 = $50
6 ║ 3 = $75
8 ║ 4 = $100
10 ║ 5 = $125
and so on...
you probably found the pattern already, so you can conclude that [cathy deposited 16 five dollar bills and 33 ten dollar bills]
Also, you should probably check if there are any mistakes when going through this since I took almost an hour writing this.
