Given,
To qualify for gold status at American Airlines one must fly less than 15,000 but at least 7200 miles each year if Miles takes a 300-mile round-trip flight when visiting his parents.
To find: How many times does Miles need to visit his parents each year to obtain gold status?
Solution:
Let x represent the time Miles needs to visit his parents.

Divide both sides by 300.

Hence, x is in the interval [24, 50).