Oxidation State Of Propene
Reconsider if a more electronegative element bound to carbon and bond to carbon will -- formally -- take the electrons, or donate the electrons in shared the bond with carbon, and how this is reflected in the oxidation state.  In each instance, watch out the signs, please.

After getting familiar with the basics, look up references focussing on organic chemistry and redox chemistry.  Albeit organic chemists tend to prefer moving electrons by hooks and arrows, there are references like this (hint: it includes an answer you may compare with the one you should find yourself, too) or even video classes like this.

Eventually, "left" and "right" will advantageously become obsolete when you gain enough credit to upload structural schemes on SE, too.