How many times longer was​ Claire's time to mow all the lawns last week than this​ week? Explain.

Claire mowed 5 lawns last week. She mowed each lawn in 7/18 hour. She mowed the same lawns this week in 5/18 hour each using her new lawn mower. How many times longer was​ Claire's time to mow all the lawns last week than this​ week? Explain.