You use different aspects here. If I say "I am eating" it means, that I am munching down on something right now, but 'I eat' means that I am generally eating (for example bread), but not at the moment of speaking. But we don't distinct these forms the same way in German. 'Ich esse' can mean both, but if it does mean 'I am eating' it is often followed by an adverb = ' Ich esse gerade'. But you have the same aspect here, so just stick to one system like the others said as well
Can i say I drink and i eat ？
That's a grammatical English sentence but it doesn't translate Duo's German sentence Ich esse, du trinkst.:
- You added an "and" that wasn't in the German sentence.
- You turned du trinkst (you drink) into "I drink" -- changed the subject pronoun.