Laura can weed the garden in 1 hour 20 minutes and her husband can weed it in 1 hour 30 minutes. How long will they take to weed the garden together?

Question

Rate problem that I don't know how to work around.

Thank You 

Answer 1

We look at how much gets done in 1 minute.

 

1/80 + 1/90 = 1/t

 

Once we apply the common denominator, 720t, we only deal with the numerators.

 

9t + 8t = 720

17t = 720

t = 42.35 = 42 mins, 21 secs