D.
It starts at 2, goes backwards 5, and ends at -3
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.
18 degrees F because
it dropped 12 degrees=10 hours
x degrees=15 hours
x is what you want to find out which is how many degrees it would drop in 15 hours.
12x15 then divided by 10 is 18.
1)
x^2 + (3y/2z) = 7
2x^2z + 3y = 14z
3y = 14z - 2x^2z
3y = 2z(7 - x^2)
y = 2/3(z)(7 - x^2)
2)
(3zx^4) /(5+z) = 2y
3zx^4 = 2y(5+z)
3zx^4 = 10y + 2yz
Y=1/3x-1. i’m not sure what point slope is but that’s slope intercept.