You have $20 to spend on taxi fare. The ride costs $5 plus $2.59 per mile. How can I write this as an inequality? Would it be like 2.50m+5<20

Yes, you are correct except for one minor error. the less than sign needs to be less than or equal to. but you probably already knew that as you cant really type those signs here. also i believe by $2.59 you meant $2.50