The total resistance is 15 Ohm, Ohm's law then allows us to calculate the current, so:

45 = 15 I,

so I =3 Amps.

The current through each or the resistors is the same as they are in series,

so for the 5 Ohm resistor we have:

V = 5x3 = 15 Volts,

and the remaining 30 Volts will be dropped accros the 10 Ohm resistor.

RonL