Answer:
5
Step-by-step explanation:
Suppose you add x liters of pure water to the 10 L of 25% acid solution. The new solution's volume is x + 10 L. Each L of pure water contributes no acid, while the starting solution contains 2.5 L of acid. So in the new solution, you end up with a concentration of (2.5 L)/(x + 10 L), and you want this concentration to be 10%. So we have

and so you would need to add 15 L of pure water to get the desired concentration of acid.
Answer:
Carlos is incorrect.
Step-by-step explanation:
We have been given that a line through the origin has a slope of
. Carlos thinks the slope of a perpendicular line at the origin will be 3.
We know that the slope of a perpendicular line to a given line is always negative reciprocal of the slope of the given line.
The slope of the perpendicular line at the origin will be negative reciprocal of
.
Let us find negative reciprocal of
as:

Since the slope of a perpendicular line at the origin is
, therefore, Carlos is incorrect.
You first divide 30 by 4 to see how long it takes him to run one mile. Then you get 30/4 which simplified is 15/2 minutes