Answer is: ΔG for methylamine is 18.85 kJ/mol.
ΔG = R·T·lnK.
ΔG is Gibbs energy.
T is the temperature on the Kelvin scale.
R is ideal gas constant.
R = 8.314 J/mol·K.
T = 25°C = 293.15 K.
Kb = 0.00044.
ΔG = - 8.314 J/mol·K · 293.15 K · ln(0.00044).
ΔG = 18836.85 J = 18.84 kJ.