posted by Pat .
current through a device is 0.30 A, and the resistance in the device is 40 Ù. How many 1.5 V batteries are required to run the device
I assume 40 Ù means 40 ohms.
V = I*R = 0.30*40 = 12 volts
That would require 12/1.5 = 8 1.5 volt batteries as the power supply.