Answer:
(- 5, 2 )
Step-by-step explanation:
Under a reflection in the line y = x
a point (x, y ) → (y, x ), thus
(2, - 5 ) → (- 5, 2 )
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.
2.. expecting something else ?
2/10 is the correct answer
Answer:
b. 9/100
Step-by-step explanation:
It helps if you have memorized the cubes of small integers. Of course, the ones needed here are ...
3³ = 27
10³ = 1000
The desired value can be simplified to ...
![\left(-\dfrac{1000}{27}\right)^{-2/3}=\left(-\sqrt[3]{\dfrac{3^3}{10^3}}\right)^2=\dfrac{(-3)^2}{10^2}=\dfrac{9}{100}](https://tex.z-dn.net/?f=%5Cleft%28-%5Cdfrac%7B1000%7D%7B27%7D%5Cright%29%5E%7B-2%2F3%7D%3D%5Cleft%28-%5Csqrt%5B3%5D%7B%5Cdfrac%7B3%5E3%7D%7B10%5E3%7D%7D%5Cright%29%5E2%3D%5Cdfrac%7B%28-3%29%5E2%7D%7B10%5E2%7D%3D%5Cdfrac%7B9%7D%7B100%7D)
