Answer:
<em>Rajan must use </em><em>0.75</em><em> liters of 5% hydrochloric acid solution and </em><em>0.25</em><em> liters of 45% hydrochloric acid solution.</em>
Step-by-step explanation:
Let us assume that, x liters of the 5% hydrochloric acid and y liters of the 45% hydrochloric acid solutions are combined.
As Rajan need total of 1 liter of solution, so
i.e
--------------------1
As Rajan needs 5% hydrochloric acid and 45% hydrochloric acid to make a 1 liter batch of 15% hydrochloric acid, hence acid content of the mixture of two acids will be same as of the final one, so

i.e
-------------2
Putting value of x from equation 1 in equation 2,





Putting the value of y in equation 1,

Therefore, Rajan must use 0.75 liters of 5% hydrochloric acid solution and 0.25 liters of 45% hydrochloric acid solution.
Answer:
or 
Step-by-step explanation:
For this exercise you can convert the mixed number to an improper fraction:
1. Multiply the whole number part by the denominator of the fraction.
2. Add the product obtained and the numerator of the fraction (This will be the new numerator).
3. The denominator does not change.
Then:

You know that he had 30 minutes in time-out, he counted spots on the ceiling for
minutes and the rest of the time he made faces at his stuffed tiger.
Then, in order to calculate the time Calvin spent making faces at his stuffed tiger, you need to subract 30 minutes and
minutes:
or 
<span>A common factor is a factor of 2 or more numbers.
the factors of 12 are: 1,2,3,4,6,12
the factors of 21 are: 1,3,7,21
1 and 3 are both common factors of 12 and 21.</span>
Answer:

Step-by-step explanation:
To factor the equation, break it into two binomials which multiply to make the equation. To write these binomials (x+a)(x+b), find factors which multiply to -20 and add to -1 for a and b.
20: 1, 2, 4, 5, 10, 20
-5+4 = -1
