Here is how I completed the problem:
I started by creating a ratio:

<em>Where 'x' is the desired amount of the 18% solution of sulfuric acid.
</em>From here, I solved for 'x':
<em>
</em>







∴You will need to add 1080ml of 18% Sulfuric Acid in order to obtain a 15% solution.
(B)
Step-by-step explanation:
Rewrite the equations into their standard forms. The first one can be rewritten as

and the 2nd can be rewritten as

Solving this system either by substitution or elimination, we get

If you add x + y, you'll get a negative number.
Answer:
I don't know
Step-by-step explanation:
I don't understand the point of this probem. It says that she has 35 envelopes best it doen't say how much can fit into each one. Maybe you ftogot some details pls reply in the comments.
Answer:
$39.59
Step-by-step explanation:
37 increase 7% =
37 × (1 + 7%) = 37 × (1 + 0.07) = 39.59
It would be 8. To solve, look at it like this: 8-b=(-2). I would then look at a number line or create one if your not to sure of yourself. 8-8=0, and then 0-2=-2. 2+8=10 (the numbers you subtracted). So the answer is 10.