Answer:
you have to provide a picture or something as well
Step-by-step explanation:
10 is the answer i think bro
Assuming a diagram similar to the one I've attached, ∠<em>YVZ</em> is a vertical angle to ∠<em>WVX</em>, which means they have an equal measure. Additionally, ∠<em>WVZ</em> and ∠<em>WVX</em> form a linear pair, which means they are supplementary (sum to 180°). That means we start out with the equation

We combine our like terms (the
<em>x</em>'s get combined, then the constants get combined) and have:

Cancel the 9 first by subtraction:

Cancel the 19 by division:

Since we know that our angle we're looking for, ∠<em>YVZ</em>, is the same measure as ∠<em>WVX</em>, we substitute 9 in for <em>x</em>:
8(9)+28=72+28=100°
148,000,000,000,000,000,000,000
Let x be the number of mm of pure alcohol to be added:
I will add the mm to express the volume in mm
100mm.(19%) + (100%).x mL = (100 mL+x mL).(40%).
Now right again without the %
100.(0.19) + x.(1) = (100+x).(0.4)
19 + x = = 40 + 04x
x - 0.4x = 40 - 19
0.6 x = 21
x = 21/0.6 and x = 35 mL. This te quantity of pure alcohol should to be added to get a solution at 40%.