(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
17/30 or .56 is your correct answer
Acceleration is simplified by assuming it is the constant -g
a=-g we integrate this with respect to time to get v...
v=-gt+C where C is the initial velocity in this case 14ft/s so
v=-gt+14 integrate again to get the height function
h=(-gt^2)/2 +14t +C we are not given an initial height so C is 0
h(t)=14t-gt^2/2 letting g=32 and neatening up a bit...
h(t)=14t-16t^2