It takes an older pump 3 times as long to drain a certain pool as it does a newer pump. Working together, It takes the two pumps 3 hours to drain the pool. How
long will it take the older pump to drain the pool working alone?
Do not do any rounding.

Step-by-step explanation:

Let x=hrs for the older pump to drain the pool

    y=hrs for the newer pump to drain the pool

We have 2 unknowns, so we need 2 equations to solve this problem:

    x=3y

    x+y=9

Using the substitution method, replace "x" with 3y in the 2nd equation and solve for "y":

   x+y=9

  3y+y=9

  4y=9

   y=9/4

Using this value for "y", solve for "x" in the first equation:

   x=3y

   x=3(9/4)  :3

   x=27/4

Check:

  x=3y                         x+y=9

  27/4=3(9/4)              27/4+9/4=9

  27/4=27/4   check     36/4=9

                                  9=9  check

Therefore, the number of hours for the older pump to drain the pool, "x", 27/4=6.75hrs.

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step-by-step explanation: