You can use the FOIL method when you have two binomials.
First, outer, inner, last
Answer:

Step-by-step explanation:
6 + 12 + 24 + 48 + 96 =
= 6 + 6 * 2 + 6 * 4 + 6 * 8 + 6 * 16
= 6 + 6 * 2^2 + 6 * 2^2 + 6 * 2^3 + 6 * 2 * 4
= 6 * 2^(n - 1)

Answer:

Step-by-step explanation:
The form of equation of line given in the problem is the point-slope form of a line. That is given by:

We need
and m (denoted by boxes)
is the y coordinate of the first set of points.
The first coordinate pair is (9,7), so
would be 7

Now, the slope (m).
It has formula

So, x_1 = 9
y_1 = 7
x_2 = 4
y_2 = -8
Substituting, we get the slope to be:

Hence, the equation of the line in point-slope is:

First you have to do 440 / 20, which is 22 cents per bottle
Next you have to do 480 / 24, which is 20 cents per bottle
20 < 22, so the 24 ounces of shampoo is the correct answer.