Answer:each class would buy 35 rolls.
Explanation:
Let x represent the number of rows of either floral sheeting or vinyl glasses that each class would buy.
The freshmen have already spent $307 on their float, plus they need to buy floral sheeting that costs $69 per roll. This means that the total cost of buying x floral sheetings would be
307 + 69x
The sophomores, who have spent $342 so far on theirs, still need to purchase vinyl grass at $68 per roll. This means that the total cost of buying x vinyl grass would be
342 + 68x
Since they are buying the same number of rolls to cover the same area, then
307 + 69x = 342 + 68x
69x - 68x = 342 - 307
x = 35