1. It takes Dustin 2 hours to shovel the snow from his driveway and sidewalk. It takes his sister 3 hours to shovel the same area. How long will it take them to shovel the walk if they work together?

Question

A: Working together, Dustin and his sister can shovel the walk in 1 1/5 hours, or 1 hour and 12 minutes?

2. A chemistry student needs to make a solution that is 70% water and 30% hydrochloric acid. The student's current mixture of 300 ml is 60% water and 40% hydrochloric acid. How much water must the student add to achieve his desired solution?

A: ?

Solve. Check your answer.

3. ((d + 2)/(d + 8)) = ((-6)/(d + 8))

A: ?

4. 4/n^2 = 7/n + 2

A: n = -4 or n = 1/2?

5. 2/t + 4/3t = 4/t + 2

A: t = 10?

6. ((x -6)/(x^2-6)) = ((-4)/(x-4))

A: ?

Answer 1

look at problem 5, it helps on the first two.

5.
2/t + 4/3t = 4/t + 2

multiply each side by 3t
6+4=12 + 6t
6t=-2
solve for t.

Now number one

time=work/rate

Now consider in 6 hours, D could do 3 walkwasy, and sister two walkways. so in six hours, they could shovel 5 walkeways, or combined rate= 5/6 walks/hr

time= 1walkwaytodo/(5/6 walway/hr)=6/5 hr

Answer 2

#3
no need for all those brackets ...
(d + 2)/(d + 8) = (-6)/(d + 8)
multiply both sides by (d+8)
d+2 = -6
d = -8

ahhh, trick question.
Notice in the original, d≠ -8
So there is no solution.

#4 correct
#5 handled by bobpursley

#6
(x -6)/(x^2-6) = (-4)/(x-4)
x^2 - 10x + 24 = -4x^2 + 24
5x^2 - 10x = 0
x^2 - 2x = 0
x(x-2) = 0

x = 0 or x = 2

Answer 3

What about #1 and #2?

Answer 4

Also, is #5 correct? bobpursley's response was somewhat unclear.

Answer 5

Reiny?