We can put the two equations together with substitution, and we get
3x + 2y = 30
Now we have a single equation in two variables, so we don't have enough information to solve for both x and y.
The answer is A. y = -2/5
31 seconds it will take to get around without it stopping



Stationary points occur where the derivative is zero. The denominator is positive for all

, so we only need to worry about the numerator.


for all

, so we can divide through:

But

for all

, so this function has no stationary points...
I suspect there may be a typo in the question.