If Sandra mixes <em>x</em> L of 65% solution with <em>y</em> L of 90% solution, then the resulting mixture has a total volume of
<em>x</em> + <em>y</em> = 500
litres, and it contains
0.65<em>x</em> + 0.90<em>y</em> = 0.75 (500) = 375
litres of alcohol.
Solve the first equation for <em>y</em> :
<em>y</em> = 500 - <em>x</em>
<em />
Substitute this into the second equation and solve for <em>x</em> :
0.65<em>x</em> + 0.90 (500 - <em>x</em>) = 375
0.65<em>x</em> + 450 - 0.90<em>x</em> = 375
75 = 0.25<em>x</em>
<em>x</em> = 300
Solve for <em>y</em> :
<em>y</em> = 500 - 300
<em>y</em> = 200
So, Sandra should mix 300 L of 65% solution with 200 L of 90% solution.
Answer:
both equations reduce to y = -1/3x -2
Step-by-step explanation:
In each case, subtract the term not containing y and divide by the coefficient of y.
1. 6y = -2x -12 . . . . 12 was subtracted from both sides
y = -1/3x -2 . . . . . . the equation was divided by 6
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2. 3y = -x -6 . . . . . . x was subtracted from both sides
y = -1/3x -2 . . . . . the equation was divided by 3
7000
1/8th in percentage form is 12.5%
12.5% of 56000 is 7000
