14/4 > 1 is what it looks like.
1 kilometer = 1000 meters so 12 kilometers = 12000 meters
10 laps (400 meters/lap) = 4000 meters
12000/4000 = 3
Answer: 3 days
When x=-1:

Ok that gives us a little more information.
If we implicitly differentiate with respect to t, from the very start, then we can apply our product rule, ya?

The right side is zero, derivative of a constant is zero.
Where x' is dx/dt and y' is dy/dt.
From here, plug in all the stuff you know:
y' = -3
x = -1
y = 4
and solve for x'.
Hope that helps!
I think the answer is B. 150 i may be wrong though