1. The problem states that a cup of soda costs 4 dollars initially, and each refill costs 0.80 dollars. 2. We need to write an equation for the total amount spent, $y$, based on the number of refills, $x$. 3. The total cost is the initial cost plus the cost of refills. 4. The initial cost is 4 dollars, and each refill costs 0.80 dollars, so the total cost is: $$y = 4 + 0.8x$$ 5. This matches option B: $y = 0.8x + 4$. 6. Therefore, the correct equation representing the amount spent on soda is $y = 0.8x + 4$.