My next door neighbour usually feeds our cat whilst we are on holiday but can't next time we are away. I',going to ask another neighbour's 16 year old daughter if she'd like to do it but will need to pay her. Will involve 1 morning and 1 evening visit to include feeding, changing water and dealing with litter tray plus responsibility for making sure cat is in at night.
I have friends' teens feed our cat when we are away (we are all very close). I usually leave them a tenner for anything up to a few days, £20 for anything over. They really don't do it for the cash though, and would regularly just pop in anyway. In your case, for two visits, I'd probably offer a tenner.