We have 10 ml of 20% acid to which we need to add "x" milliliters of 100% acid to make 50% acid.
.20 * 10 + 1.00x = .50 * (10 +x)
in which "x" is the volume of the 100% acid to be added.
2 + x = 5 + .5 x
.5x = 3
x = 6 milliliters
Source:
http://www.1728.org/mixture.htm
Scroll down to problem B
su.ck on D.EEZ NUTS b.itch XD
Answer:
1 year
Step-by-step explanation:
Let the first number be represented by "x".
Let the second number be represented by "y".
"Four times a number..." = 4x
"... minus 5..." = 4x - 5
"... times another number..." = y(4x - 5)
"... is equal to 21." = y(4x - 5) = 21
y(4x - 5) = 21
"Three times the sum of the two numbers (x & y) is 36." = 3(x +y) = 36
3(x + y) = 36
y(4x - 5) = 21
1) solve for "y"
1) y(4x - 5) = 21
2) 4xy - 5y = 21
3) 4xy/4x - 5y = 21/4x
(what you do to one side of the equals sign, you must do to the other so 4x cancels out on the left side, and on the right side you have to divide 21 by 4x)
4) y - 5y/-5 = 5.25x/-5
5) y + y = -1.05x
6) 2y = -1.05x
7) 2y/2 = -1.05x/2
8) y = -.525x
2) substitute "y" in for the second equation
1) 3(x + (-.525x)) = 36
(notice how you now only have x's in this equation)
3) solve for x
1) 3x - 1.575x = 36
2) 1.425x = 36
3) 1.425x/1.425 = 36/1.425
4) x = 25.3
4) finish finding "y" in either one of the equations using the answer you got for "x"
1) y(4(25.3) - 5) = 21
2) y(101.2 - 5) = 21
3) y(96.2) = 21
4) 96.2y = 21
5) 96.2y/96.2 = 21/96.2
6) y = .22
5) check your work by substituting the two answers back into one of the equations
1) .22(4(25.3) - 5) = 21
2) .22(101.2 - 5) = 21
3) .22(96.2) = 21
4) 21.164 = 21
(round down to get the answer)
The equation that represents the total amount earned is y = $9x.
The amount he would earn if he worked 180 hours is $1,620.
<h3>How much would he earn?</h3>
If the amount he earns is proportional to the hours worked, it means that as the number of hours worked increases, the amount he earns also increases.
To determine the equation, the amount earned per hour has to be determined.
Pay per hour = 18 /2 = $9
y = $9x
The amount earned if Felix worked for 180 hours : y = $9(180)
y = $1,620
Here is the complete question:
Felix worked at a music shop during the summer. The table below shows some of Felix’s hours and earnings. The amount of money he earned is proportional to the number of hours he worked.
2. Let x represent the number of hours he worked, y represents the amount of money he earned.Write an equation that represents this relationship.
3. If Felix worked 180 hours, then how much money did he earn?
To learn more about multiplication, please check: brainly.com/question/3385014
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