Answer
Acetic acid > ethanol > methylamine
Work Step by Step
The $pK_a$ of acetic acid is 4.74, ethanol is 15.9, and methylamine is approx 40. Thus, Methylamine is the weakest acid and acetic acid the strongest.
The stabilities of the conjugate bases can also be used to determine the strongest and the weakest acid. The conjugate base of acetic acid is resonance stabilized (so most acidic), the conjugate base of ethanol has the negative charge on the most electronegative atom oxygen, and the conjugate base of methylamine has a negative charge on the nitrogen which is mildly electronegative. So methyl amine has the least stabilized conjugate base so it is the weakest and acetic acid has the most stabilized conjugate base so it is the strongest acid.
