Answer: (f)
Step-by-step explanation:
Given
Line that passes through
and 
Using two point form, equation of a line is given by

Insert the values

Thus, option (f) is correct
Box volume = height * width * length. In this problem we want the length, so we solve the given equation for length:
720 in^3
length = -------------------- = 12 in
(15 in)(4 in)
The box is 12 inches long.
To solve this problem, we are going to set up an equation. Let the number that we are trying to find be represented by the variable x. If we plug in the numbers that we know, we get the following equation:
3x/4 = 24
To simplify this equation, we need to multiply both sides by 4, to begin getting the x alone on the left side of the equation.
3x = 96
Finally, we need to divide both sides by 3, to get rid of the coefficient that is being multiplied to x.
x = 32
Therefore, the number that you are trying to find is 32.
X = number of cds on the rack
x + 7 = 30
x = 30 - 7
x = 23 <== so there are currently 23 cds on the rack