Band A.
• Charges $600 to play for the night.
Notice that this cost is to play the whole night, it's a fixed cost.

Band B.
• Charges $375 plus $10 for each ticket sold.
,
• The sophomore sold 30 tickets.
This band has a fixed cost plus a fee of $10, which is $300 more because they sold 30 tickets.
So, the cost of this band would be

Therefore, Band B will charge more than Band A.