math help:A nurse wishes to add water?

Question

A nurse wishes to add water to 30 ounces of a 10% solution of whatever to dilute it to an 8% solution. How much water will she have to add?
x+.10(30)=.08(x+30)?
I am old an lost!!!

pure liquid such as the water is factored at 0%?

Answer 1

It's percentage times amount plus percentage times amount equals percentage times amount, where the percentage is the fraction of the amount that's the active or valuable ingredient. Water is 0% active ingredient, so

0%(x) + 10%(30) = 8%(x+30)
300 = 8x + 240
60 = 8x
x = 7.5 oz.

Answer 2

Well, I donno the exact formula for it. But here is the logical approach

10% of 30 ounce = 3 ounce of whatever

So, we have 3 ounce of whatever in the solution.
Use the cross multiply approach to find total ounces needed to reduce the whatever to 8%

for 100 ounce solution, need 8 ounces
for x ounce solution, need 3 ounce

solving for x, 3 * 100/8 = 37.5

So, you need to add 7.5 more ounces of water.

To have it as 1 step formula, x = (30/10) / 0.08

Answer 3

solve for x.