Answer:
1 hour.
Explanation:
Mari has a part time job.
She earns $7 per hour.
She makes at most $13.20 per week.
1 hour gives $7
How many hours gives $13.20 ?
Cross multiplying gives;
× 1 hour = 1.885714286 hours
Since she can't get a payment for 0.885714286 hours, she will have to work for 1 hour.