hello
to solve this question, we ave to write out equations for the scenarios
the total number of bottle is

the cost of the bottles is equal to b

where x is representing the cost of each bottle
also, we were told she paid $0.25 and she's left with $3.20
let's put that down

we can solve this and find the value of b

since we know the value of b, we can easily find the cost of each bottle

from the calculations above, she earned $3.45 from recycling 23 bottles and the cost of each bottle was $0.15