Jannette can repair a refrigerator in 60 minutes. Liza can repair a refrigerator 20 minutes faster. If they work together, how many minutes does it take them to repair the refrigerator

24 minutes. Assuming that 2 people who will repair a refrigerator equally fast will do it twice as fast when working together:

Jannete repairs 1/60 refrigerator per minute.

Lisa repairs 1/40 refrigerator per minute.

Togheter they repair 1/60+1/40 = 1/60 + 1,5/60 = 2,5/60=5/120=1/24 refrigerator per minute

thus it will take them 24 minutes