Answer:
28 5 dollar bills
12 10 dollar bills
Explanation:
You can write two equations to model this situation'
x will be the number of 5 dollar bills
y will be the number of 10 dollar bills
x+y=40
5x+10y=260
There are a couple of ways you can solve this but but I will be doing it through substitution because that looks easier (I can explain other methods if you're interested)
So we have x+y=40
If I subtract y from both sides and divide by -1 we get
-x+40=y
We can then plug this value in for y in the second equation
5x+10(-x+40)=260
Distribute the 10 and combine like terms to get
-5x+400=260
subtract 400 from both sides and divide by -5 to get
x=28
This means that there are 28 5 dollar bills. We can plug this value back in for x into our first equation to solve for y
28+y=40
Subtract 28 from both sides
y=12
This means that there were a total of 28 5 dollar bills and 12 10s
I doubled checked this in desmos and it checks out