Answer
$ I = 0.5 A$
Work Step by Step
We are given that $R$ is same for both circuits.
In first circuit
$V =IR \\ \implies R=\frac{V}{I} = \frac{9.0 v} {3.0A} = 3.0 \Omega$
Now in second circuit
$V =IR \\ \therefore I =\frac{V}{R} =\frac{1.5v}{3.0\Omega} = 0.5 A$
Hence current in other circuit is $0.5A$
