Lets call x the amount of 18% solution and y the amount of 40% solution, and write as equations the info of the problem:
18x + 40y = 10(20)
x + y = 10
lets multiply the second equation by -18 and add to the first:
18x + 40y = 200
-18x -<span> 18y = -180
</span>----------------------
0 + 22y = 20
y = 20/22 = 10/11
and substitute in the original equation:
x <span>+ y = 10
</span>x = 10 - y
x = 10 - 10/11
x = 110/11 - 10/11
x = 100/11
so they have to use 100/11 liters of 18% solution and 10/11 liters of 40% solution
Answer:
7/25
Step-by-step explanation:
First we need to determine how many total marbles
9blue+7red+4green+5purple = 25 marbles
P(red) = red/total
= 7/25
Answer: Box A, 2.777
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Explanation:
When using a calculator or long division, you should find that
7/9 = 0.7777...
where the 7s go on forever
So we can say that 7/9 = 0.777 approximately. You could argue that the last '7' would round up to an '8' and we could say 7/9 = 0.778; however, I'll stick to the first value so that it matches with the answer.
Since 7/9 = 0.777, this means 2 & 7/9 = 2 + 7/9 = 2 + 0.777 = 2.777 which is box A.
Answer:
A
Step-by-step explanation:
An excluded value is any value of x that makes the denominator of the rational expression zero as this would make the expression undefined.
For expression A
The denominator will be zero when x² - 4 = 0
x² - 4 is a difference of squares, thus
(x - 2)(x + 2) = 0
x - 2 = 0 ⇒ x = 2
x + 2 = 0 ⇒ x = - 2
The excluded values of x are x = ± 2 ⇒ A
