7 L of one solution is mixed with 3 L of another, making a new solution with a total volume of 10 L and concentration 29%. This means the new solution contains
(10 L) * 29% = (10 L) * 0.29 = 2.9 L
of acid.
Let the concentration of the first solution be <em>c</em>%. Each liter of the 15% acid solution contributes 0.15 L, and each liter of the solution of unknown concentration contributes 0.01<em>c</em> L of acid. To end up with a total of 2.9 L of acid, we would get
7 * (0.01<em>c</em> L) + 3 * (0.15 L) = 2.9 L
Solve for <em>c</em> (we can omit the units):
0.07<em>c</em> + 0.45 = 2.9
0.07<em>c</em> = 2.45
<em>c</em> = 35
So the first solution has a concentration of 35%.
Ok well if you have 8 students and 2 boards divide the students by 2.
8/2=4
now, if each student wanted to paint part of a board and there are four students then divide 1 by 4
1/4=.25 or 1/4
so 4 students can paint one board while the other 4 students pain the other board
21 its 21 because it is 21
Answer:
5
Step-by-step explanation:
3+x