Remember some basic rules

and
![x^ \frac{m}{n}= \sqrt[n]{x^m}](https://tex.z-dn.net/?f=x%5E%20%5Cfrac%7Bm%7D%7Bn%7D%3D%20%5Csqrt%5Bn%5D%7Bx%5Em%7D%20%20)
so

1/2-2/7=
7/14-4/14=
3/14

Answer:
The original cost of the DVD was $21`.59
Step-by-step explanation:
In order to find this, you first must note that the new price is 88% of the older price. We get this since there was a subtraction of 12%.
Now knowing that, we can divide the new price by the percentage paid and it will give us the original price.
$19/88% = Original Cost
19/.88 = Original Cost
$21.59 = Original Cost
Answer:
Step-by-step explanation:
Given that the number of males in the classroom is three more than twice the number of females.
the total number of students is 57
Let x be the no of males then no of females = 
Also we have 3 more than twice no of females as

This equals x

No of males = 39, no of females = 18
Beginning with the function y = sin x, which would have range from -1 to 1 and period of 2pi:
Vertical compression of 1/2 compresses the range from -1/2 to 1/2
Phase shift of pi/2 to the left
Horizontal stretch to a period of 4pi, as the crests are at -4pi, 0, 4pi
Vertical shift of 1 unit up moves the range to 1/2 to 3/2
So the first choice looks like a good answer.