When do you use dobrzy vs dobre?
Dobrzy - masculine personal plural (used only for groups of people containing at least one man)
Dobre - not masculine-personal plural (used for... well, everything else).
Also the neuter singular looks the same as not masculine-personal.
There isn't a situation where you can use dobra? Since kanapka ends with an 'a'.
yes but here the lesson deals with plurals and kanapka is not plural