175 mL at 25% concentration of alcohol contains 0.25 (175 mL) = 43.75 mL of alcohol. If <em>v</em> is the amount of the 70% solution that you use, then that amount contains 0.7<em>v</em> mL of alcohol.
Mixing these two yields a total volume of 175 mL + <em>v</em>, and it contains 43.75 mL + 0.7<em>v</em> alcohol. You want to end up with a concentration of 45%, which means the ratio of the amount of alcohol to the total volume needs to be 0.45:
(43.75 mL + 0.7<em>v</em>) / (175 mL + <em>v</em>) = 0.45
Solve for <em>v</em> :
43.75 mL + 0.7<em>v</em> = 0.45 (175 mL + <em>v</em>)
43.75 mL + 0.7<em>v</em> = 78.75 mL + 0.45<em>v</em>
0.25<em>v</em> = 35 mL
<em>v</em> = 140 mL
Answer:
9
Step-by-step explanation:
UT^2 = UV * UW
6^2 = (x - 7)(x - 7 + 5)
36 = (x - 7)(x - 2)
36 = x^2 - 2x - 7x + 14
x^2 - 9x - 22 = 0
(x - 11)(x + 2) = 0
x - 11 = 0 or x + 2 = 0
x = 11
UW = x - 7 + 5
UW = 11 - 7 + 5
UW = 9
Answer:
<h2>
y = 3.5x + 15</h2>
Step-by-step explanation:
Number of months is x, and number of pairs of shoes after each month is y.
7 new pairs of shoes every 2 months means that after each month:
y = 7/2 x
We need to add the 15 pairs from start.
y = 3.5x + 15
