Calculate what mass of natural gas burns when water is heated on a kitchen stove in a kettle

Calculate what mass of natural gas burns when water is heated on a kitchen stove in a kettle with a volume of 3 liters to the boiling point. The specific heat of combustion is 4.4.

Energy consumed for heating:
Q1 = m1 * q, where m is the mass of the gas, q is the specific heat of combustion of the gas (q = 44 MJ / kg).
The amount of heat received by water:
Q2 = c * m2 * ∆T, where c is the specific heat capacity of water (c = 4183 J / (kg * K)), m2 is the mass of water (m = ρw * V, where ρw is the density (ρw = 1000 kg / m ^ 3), V-volume (V = 3 l = 3 * 10 ^ -3 m ^ 3)), ∆T-temperature difference (assumed initial temperature 20ºС, then ∆T = 80 ºС).
Since Q1 = Q2, then
m1 * q = c * ρw * V * ∆T;
m1 = s * ρw * V * ∆T / q = 4183 * 1000 * 3 * 10 ^ -3 * 80 / (44 * 10 ^ 6) = 0.023 kg
Answer: The mass of natural gas is 0.023 kg.