The balance will be a little different for every settlement! You can usually rely on one farm and and one bakery until around 20 total population, like when you're first starting out. I recommend a bakery for every 2-3 farms, and about a farm every 15 pops. But don't use solid numbers, always base it around your resource needs. For example, maybe i'm at 50 pops and i have 3 farms and 3 bakeries.
Otherwise it can depend a lot on your surplus cap.