Relationship: folder unit price × folder quantity+ink unit price × ink quantity = total payment amount.

Solution: Set X yuan per bottle of ink.

3.5+ 12x=25 10

12x=25 10-3.5

12x=2506.5

x=208.875

x≈208.88

Description: There must be something wrong with your topic, which is unrealistic! How can a bottle of ink cost 208.88 yuan? ! )