# algebra

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if mary takes 3 hours to mow a lawn and sally takes 5 hours how long will it take them to mow it together

• algebra -

Mary's rate = lawn/3
Sally's rate = lawn/5
combined rate = lawn/3 + lawn/5
= 8lawn/15

time = lawn/(8lawn/15) = 15/8 or 1.875 hrs = 1 hour and about 53 minutes

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