The 7th and 8th grade classes are selling raffle tickets to raise money for a school dance. The 7th graders are selling tickets for $3.25 each and have raised $650, so far. The 8th graders are selling tickets for $4.00 each and have raised $400, so far.
Which equation can be used to find n, the number of tickets each grade need to sell in order for them to raise the exact same amount of money?