She used her magic to sped up the chore.

After recieving the orders from Byleth, Annette and Mercedes began to clean the kitchen as much as they could, with the former focusing on cleaning the floor, and the latter focusing on focusing on cleaning the dishes ,neither of them had to clean the ovens, as that was a task for someone else, and so, they only had to not screw up anything.

Annette, was just more happy to help with the chores after her previous incident, as was Mercedes, however, after an hour or so doing nothing but scrubbing the floor with the mop, her arms were beginning to hurt, making her consider if perhaps she had chosen the wrong task.

"Hey Mercie, do you wanna change task ?, i'm tired of mopping the floor", she offered to her.

"If that's what you want, of course then", Mercedes politely replied, and so, they changed tasks, with Annette's new task being to clean the dishes.

However, not soon after the change, Annette too began to get bored of cleaning dishes, as despite Mercedes's previous progress, there was still a lot of them to clean, not to mention, that even the clean ones they had to be put in order.

"At this rate we won't ever finish", Annette said a she pouted, "But what if..?", she thought, for she was about to do something new to sped things on. And that turned out to be her magic, or more accurately, the levitation spell, that way, she could clean and order dishes more than twice as fast.

"heh, i'm not sure if this counts as cheating, but i'm liking it", she joked as she continued on using magic to do her chores. And so, she did, as before anyone could see her, she was already down to the last plate...