Ohhhhh its called a input machine
The concept that we need here to give a proper solution is mutual inductance.
The mutual inductance is given by the expression

Where,
I = current
N = Number of turns
Flux through the solenoid.
Part A) Then we have in our values that,



Replacing in the equation,


Part B) Here is required the Flux, then using the same expression we have that

We conserve the same value for the Inductance but now we have a current of 2.6, then


Therefore the flux in Solenoid 1 is 
Answer:
V = 38.0 L
Explanation:
As we know that number of moles will remains conserved inside the balloon
so we will have

here we have

now we have







You are dealing with pulleys?
can be done with addition of the two equations to eliminate T.

+

=

we can cancel m₁ by dividing both sides by it, assuming mass is not zero

a₂ = 6.125 m/s² ( do significant digits if you need to)