What are two things that's similar to a knuckle

Mary had at least an 80% on her test write an inequality to represent this situation

How do you solve a question like this?

The water company charges a residential customer $41 for the first 3,000 gallons of water used and $1 for every 200 gallons used over 3000 gallons. if the water bill was $58 how many gallons of water were usedanswersa 3400 gallonsb 6000 gallonsc 6400 gallons d 7000 gallons