Answer: 0.85 or %85
Fraction = 68 over 80 divide by two twice 17 over
20
Percent = 68/80 = 0.85 x 100 = 85%
Decimal = 0.85
The difference of two squares factoring pattern states that a difference of two squares can be factored as follows:

So, whenever you recognize the two terms of a subtraction to be two squares, you can factor it as the sum of the roots multiplied by the difference of the roots.
In this case, the squares are obvious:
is the square of
, and
is the square of 
So, we can factor the expression as
![(x+2)^2 - (y+2)^2 = [(x+2)+(y+2)] - [(x+2)+(y+2)]](https://tex.z-dn.net/?f=%20%28x%2B2%29%5E2%20-%20%28y%2B2%29%5E2%20%3D%20%5B%28x%2B2%29%2B%28y%2B2%29%5D%20-%20%5B%28x%2B2%29%2B%28y%2B2%29%5D%20)
(the round parenthesis aren't necessary, I used them only to make clear the two terms)
We can simplify the expression summing like terms:
![(x+2)^2 - (y+2)^2 = [(x+2)+(y+2)][(x+2)-(y+2)] = (x+y+4)(x-y)](https://tex.z-dn.net/?f=%28x%2B2%29%5E2%20-%20%28y%2B2%29%5E2%20%3D%20%5B%28x%2B2%29%2B%28y%2B2%29%5D%5B%28x%2B2%29-%28y%2B2%29%5D%20%3D%20%28x%2By%2B4%29%28x-y%29%20)
21 chaperones are needed for 420 students.
Step-by-step explanation:
No. of juniors = 148
No. of seniors = 272
Total = 148+272 = 420 students
3 chaperones = 60 students
1 chaperone = 
Ratio of chaperon to students = 1:20
Let,
x be the number of chaperons for 420 students.
Ration of chaperones to students = x:420
Using proportion
Ratio of chaperones to students :: Ratio of chaperons to students

Product of mean = Product of extreme

Dividing both sides by 20

21 chaperones are needed for 420 students.
Keywords: ratio, proportion
Learn more about ratios at:
#LearnwithBrainly
Answer:
X=6, Y=-1
Solved using substitution