Solution:

1. A quantitative variable is a phenomenon measured in amounts, that is, numerical units. For example, a numerical score is a quantitative variable.
2. The measurement is based on a scale of 1 to 4.

Solution:

1.    3x + 4y=25
2.    2x – 5y=9

We could rewrite these as follows by multiplying the first equation by 5 and the second by 4:

1.    15x + 20y = 125
2.    8x  – 20y = 36

If we add the above two equations, we can eliminate y:

23x = 161

So x =3D 7, and plugging this into the first equation we can figure out
y:  21 + 4y =3D 25,

so y = 1

Solution:

First recognize that this is in the form of (x²-a²), which can always be factored as (x+a)(x-a). If you multiply these two terms, you get x²-ax+ax-a², which is equal to x²-a².

So in this case, we can see that a=3,

so  x²-9

=  x²-3²

= (x+3)(x-3)

Solution:

You can simply 12 – ( x + 3 ) +10 by rearranging the terms:

1. 12 –x -3 +10
2. 19-x

Solution:

1. Let’s call the number of cookies Cara made “x”
2. First she sold three fifths of x(.6x)
3. The remaining amount is two fifths of x(.4x)
4. Then she one fourth of x;two fifths of “x” (.25*.4x = .1x)
5. .6x=.1x+200
6. .5x=200
7. x= 400

Solution:

• 2(x – 5) = -11
• 2x – 10 = -11
• 2x = -1
• x = -0.5