Independent variable (IV): something the scientist can change.
Thus, in this case, the IV can be the weight of the person.
(a) need to find the number of books, we'll call it "b". then the money (6w) minus the cost of books (17b) equals change left over (w)
6w - 17b = w
6w - w = 17b
5w = 17b
(5/17)w = b
(b) if w = 34
(5/17) *34 = b
10 = b
4 feet? 20/5=4? Not too sure
Slope-intercept form is

, where m is the slope and b is the y-intercept.
Here, we first need to distribute the 1/3.

Next, we add 3 to both sides of the equation.