You could buy screw-on ends of the proper type, cut the old ends off and wire the proper onto the existing cords.
You could resell the cords and buy new.
You could buy a sack of wire nuts, cut all the ends off and hardwire everything.
You could buy a 6-20 socket to replace the wall outlet and work from that.
You could invent time travel?
all of these are valid.
The cords you have dont match the outlets - there isnt really a cheap solution to this besides re installing the correct outlet or buying the correct cord