Expert: Sherry Wallin - 4/29/2009

Question
Hello I need ur help once again I hope bim not burden u with these but thanks for the previous thing please help and answer them god bless

Perform the indicated operation

1. 1/5y-1 times 125y^3 - 1/y-1
2. a^2 - 81/a+9 divide (a-9)^2 /9-a
3. x^2 + xy + xz/xy^2 - xz^2 divide x-y-z/y^2 - z^2
4. k^4 - 16/k^2 + 4k + 4 divide k-2/2k+4

Combine the following fractions

5. x/4 + 2x-1/3 (-) x+2/6
6. 1/a (-) 6/bc + 3/ac
7. 6/3x + 9y (-) 2/x - 3y
8. a/a^2 - 3a - 4 (-) a-1/a^2 - 6a + 8
9. 12x - 4y/x^2 - y^2 (+) 4/y - x (-) 8/x+y

Simplify the complex fractions
              x
       1 +----
              y
10.  --------------
              x
        1 - -----
              y

11. 8x + 2
   ------------- = 10  
         5

12. 2a / 3 - a/6 = 5a/12 - 3/4

13. y-1/4  + 1 = 6 - 5y+10/10

14. 2x+1/3x-12 = 12/x^2 - 16  -  1-2x/3x + 12

Solve the word problems

15. A certain solution is 75% water. Another solution is 90% water. How much of each solution  is 90% water. How much of each solution should be used to produce a new solution of 300ml that is 85% water?

16. Jake can do a certain job in 50 min. Chris can do the same job in 1 1/4 hours. How long will take them to complete the job if they work together?

Answer
Hi again I will answer just a few and again I admonish you to take  course so you can learn and teach. You are cheating your child if you are not allowing him/her to learn this the right way.

15) Let x = amount of solution that is 90% water then 300 = x is the amount that is 75% water

.9x + .75(300-x) = .85(300)
90x +75(300-x) = 85(300)
90x + 22500-75x = 25500
15x + 22500 = 25500
15x = 3000
x = 200

so 200 ml of 90% water and 100ml of 75% water will make a solution of 300ml water that is 85% water

16) Jake's rate of work is 1job/(5/6)hr and Chris' rate is 1job/(5/4hr)
Together they complete 1 job in this way. (6/5)x + (4/5)x = 1 ->
(10/5)x = 1 or 2x = 1 or x = 1/2. So together Jake and Chris can complete the job together in 30 min

Math Prof