Question

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?

120 minutes
40 minutes
24 minutes
20 minutes

Answer 1

@jim_thompson5910

Answer 2

`Jannette can repair a refrigerator in 60 minutes. Liza can repair a refrigerator 20 minutes faster`

question: how long does it take Liza to repair the fridge if she worked on her own (with no help) ?

Answer 3

any ideas @Gabylovesyou ?

Answer 4

60 - 20 ?

Answer 5

which is 40 min, yes

Answer 6

x = time it takes Jannette to do the job alone (with no help)
y = time it takes Liza to do the job alone (with no help)
z = time it takes to do the job if the two worked together


All times (x,y,z) are in minutes


In this case,
x = 60 min
y = 40 min
z = unknown


\[\Large \frac{1}{x} + \frac{1}{y} = \frac{1}{z}\]

\[\Large \frac{1}{60} + \frac{1}{40} = \frac{1}{z}\]

solve for z

Answer 7

24 ? sorrry wifi is slow...

Answer 8

yes, z = 24