Two last math questions--Can any one help me so I understand?

Question

1) A nurse is mixing a 15% bleach solution with a 40% bleach solution to get 20 liters of a 25% solution. How much of each solution must he use? Answer will be in liters.

2) If a vehicle has traveled 406 miles in 7 hours, what speed did it average?

Thanks to all! =)

Answer 1

im not sure about the first one, but the second one is simple- you're just making it difficult.

just divide 406 by 7 and you get the mph

hope this helps :)

Answer 2

if you add one liter of 15% with one liter of 40% you now have two liters of 25%. 10 liters of each will answer your problem.

406 units of travel divided by 7units of time.

Answer 3

let x be the amount of 15% bleach solution.  Since you will end up with 20 liters of mixture, 20-x is the amount of 40% bleach solution.

.15*x+.4*(20-x)=.25*20

Multiply by 100 to get rid of the decimals

15x+40(20-x)=25*20

15x+800-40x=500

-25x+800=500

-25x=500-800

-25x=-300

x=6 liters of 15% solution

14 liters of 40% solution

2) Distance = rate times time

406=r*7

406/7=r

r=58mph

_/

Answer 4

2 is just 406 divided by 7, or 58mph.

#1 I am not too sure about

Answer 5

2...very easy....

406 divided by 7 = 58 mph