Green’s Dictionary of Slang

it is possible, it is within my power; thus no can do, it is impossible.

1904		Kipling ‘Their Lawful Occasions Pt I’ in Traffics and Discoveries 123: ‘Mr. Hinchcliffe, what’s her extreme economical radius?’ ‘Three hundred and forty knots, down to swept bunkers.’ ‘Can do,’ said Moorshed.
1958		R. Prather Scrambled Yeggs 131: She pushed her lips together and thought for a minute. ‘Can do, I think. Now?’.