Answer: Let's assume Julia can afford to buy "x" stops on her train ticket.
The total cost of the train ticket can be calculated as follows:
Total Cost = Initial Fee + (Fee per Stop × Number of Stops)
Given that the initial fee is $5 and the fee per stop is $2.75, the equation for the total cost of the ticket is:
Total Cost = 5 + 2.75x
Julia has $21, and she wants to spend this amount on the ticket. So, we can set up an equation:
Total Cost ≤ 21
Substitute the expression for the total cost:
5 + 2.75x ≤ 21
Now, solve for "x":
2.75x ≤ 21 - 5
2.75x ≤ 16
x ≤ 16 / 2.75
x ≤ 5.818181...
Since Julia cannot buy a fraction of a stop (she must buy a whole number of stops), she can afford to buy a maximum of 5 stops on her ticket.
If she buys 5 stops, the total cost will be:
Total Cost = 5 + 2.75 × 5 = 5 + 13.75 = $18.75
With $21, she can afford the ticket with 5 stops and will have $21 - $18.75 = $2.25 left.