Like, puffon and zoiDman stated, then math is optional, and most just use a DIY calc. Or take 100ml of base and 3ml of flavor, shake and you've got a 3'ish% flavored liquid. You can buy your base premade at your nic-level, if wanting nic, but it's easy with a calculator to make your own base too.
There are a wealth of non-oil based flavours, and if you're just starting out, and want something simple, then e.g. inawera has a bunch of good flavors that only takes a couple percent and many works fine standalone, e.g. authentic great fruit flavors etc.
Everything new takes some research to master and this is no different, but requiring advanced math skills is not one of them, lol
