I'm guessing it is 10? or 7?

(a) For dx/dt=6, dy/dt = 2·6 = 12
(b) For dy/dt=2, 2 = 2·dx/dt ⇒ dx/dt = 1
_____
The value of x is irrelevant for this question.
=====
If your function is 2^x +1 or 2^(x +1), it needs to be written as such. The answer above applies to the function given.