Answer:
10 or 1000 in hundreds of units
Step-by-step explanation:
Given the supply curve of portable radio rentals:

and the demand curve for portable radio rentals:

we need to find the equilibrium of these two curves ( replace either's right hand side on the other's left hand side)
we have:

solving we have
or
in hundreds of units
Now the noise is equal to 3, therefore, we have to find the social supply curve by adding 3 to the first supply curve. following:

We find the intersection bewteen the social supply curve and the demand curve ( social equilibrium rental ):

Which gives
or
in hundreds of units.
Now that we integrated the noise into our considerations, the equilibrium rental exceeds the social equilibrium rental by 10 (50-40) (1000 in hundreds of units)