First, we have to find the number of volts requires using Ohm's Law.
[tex]V=I\cdot R[/tex]Where I = 0.30 A and R = 30 ohms. Let's replace these values and solve for V
[tex]V=0.30\cdot30=9V[/tex]Once we have the amount of voltage, we can divide it by 1.5V to get the number of batteries
[tex]n=\frac{9V}{1.5V}=6[/tex]