The amount of energy of a photon is proportional to the frequency.
We can obtain the answer easily if we assume the gas here is an ideal gas. We can use t he expression:
PV = nRT
we set nR/V = k
P/T = k
P1/T1 = P2/T2
when P2 = 3P1
P1/10 = 3P1/T2
T2 = 30 degrees Celsius
Power = current x voltage
So the power is 7 x 110 = 770 W = 0.77kW
0.77 x 13 = 10.01 kWh
10.01 x 10 cents = 100.1 cents (is this 1 dollar? Idk I use a different currency)