A. In case you have trouble finding factors of -4 that add to -3, you can read the coordinates of the zeros from the given graph and use those to find the factors.
-4 = -4·1 = -2·2 = -1·4 . . . . . sums of these factors are -3, 0, +3
The factors of -4 you can use in your factors of the equation are -4 and 1:
f(x) = -16(x-4)(x+1)
B. The zeros are the values of x that make the factors become zero. For the first factor, that is x=4. For the second factor, that is x=-1. (You can see these x-intercepts in the graph.)
C. The problem statement tells you f(x) = 0 means the paper airplane is at the level of the water.
D. Since we start measuring time at t=0 when we release the airplane, the value t=-1 has no meaning in this context. No, only one zero has real-world meaning.
E. Since x is the number of seconds since the airplane was thrown, the fact that x=4 when f(x) = 0 means it takes 4 seconds for the airplane to hit the water.