Final answer:
Louisa paid $8.25 for the entry fee at Lakeside amusement park.
Step-by-step explanation:
To determine how much Louisa paid for the entry fee, we need to subtract the cost of the ride tickets from the total amount she spent. Let's assume the entry fee is represented by 'x'.
Given that Louisa spent $30.75 on the entry fee plus 15 ride tickets and the ride tickets cost $1.50 each, we can set up the equation:
x + 15 * $1.50 = $30.75
We can simplify the equation to:
x + $22.50 = $30.75
To isolate 'x', we subtract $22.50 from both sides of the equation:
x = $30.75 - $22.50
x = $8.25
Therefore, Louisa paid $8.25 for the entry fee.