Question

Can someone help me answer B and C? I'm really stuck on those 2 questions....

Answer 1

          We know that 3 friends can paint the room together for 8 hours. John can paint it alone for 12 hours and Rick can paint it alone for 12 hours ( Answer a.).
          b. The hourly rate for John, Rick and Molli, when working together is:
          1 /8  ( rooms per hours )
          c. Hourly rate for John: 1 /12.
          Hourly rate for Rick : 1 / 12.
          An equation is: 1/3 = 1/x + 1/12 +1/12 ( 1/x is the hourly rate for Molli, that we don`t know ).