Hey there! I'm happy to help!
Let's set this up as a system of equations, where x is equal to the number of 10 dollar bills and y is equal to the number of 50 dollar bills.
10x+50y=1080
x+y=28
We want to solve for x or y. We can rearrange the second equation to find the value of one of the variables.
x+y=28
Subtract x from both sides.
y=28-x
Now, we have a value for y. So, we could replace the y in the first equation with 28-x and the solve for x.
10x+50(28-x)=1080
We use distributive property to undo the parentheses.
10x+1400-50x=1080
We combine like terms.
-40x+1400=1080
We subtract 1400 from both sides.
-40x=-320
We divide both sides by -40.
x=8
Since there are 28 total bills, this means that there must be 20 50 dollar ones because there are 8 10 dollar bills.
Have a wonderful day! :D