Powrer factor of circuit = 1
$R/Z= 1$ so $ R=Z $
$ Z= \sqrt {(wL-1/wC)^2 +R^2}$
but Z=R so,$
R^2=R^2 +(wL-1/wC)^2$
So $wL= 1/wC $
$1/wC= 40$
where $R $ would be resistance due to box only , as we don't see any other resistance
(provided the ammeter was ideal)
So for box,
Let $Z' $ be reactance of box.

So $ R/Z'= $
$ R/wL=3/5==> R/40 =cot\theta=3/4$
this gives R=30
Now R= Z for complete circuit,
so I= 3A ,
I think it would be 3A then .