11) Adam can mop a warehouse in ten hours. Wilbur can mop the same warehouse in nine

hours. If they worked together how long would it take them? Be sure to respond in a complete

sentence that explains your answer in relation to the question.

12) Working together, Jessica and Jill can install a new deck in 6 hours. Had she done it

alone it would have taken Jill 15 hours. How long would it take Jessica to do it alone? Be sure to

respond in a complete sentence that explains your answer in relation to the question.

Step-by-step explanation:

11) Adam's speed is 1 warehouse / 10 hours.

Wilbur's speed is 1 warehouse / 9 hours.

Their combined speed is:

1/10 + 1/9

9/90 + 10/90

19/90

Distance = rate * time

1 warehouse = 19/90 warehouse/hr * t

t = 90/19 hours

t ≈ 4.74 hours

Working together, they can mop the warehouse in 4.74 hours.

12) Jessica and Jill's combined speed is 1 deck / 6 hours.

Jill's speed is 1 deck / 15 hours.

Jessica's speed is:

1/6 - 1/15

5/30 - 2/30

3/30

1/10

Distance = rate * time

1 deck = 1/10 deck/hr * t

t = 10 hours

Working alone, it takes Jessica 10 hours to install a new deck.