It absolutely is 1/4th of what remains. Rachel will be left with 9 and Tracey will have 7. They're not going to say 'what remains of the quarter tracy took' because it's nonsensical. Tracy took a quarter so there's nothing that remains of the quarter tracy took. they're not going to mean 'there is only one quarter left and tracy takes It' either, because that also is nonsense. The only meaning that makes any possible sense, then, is 'tracy takes one quarter of what remains', which is 12/4 = 3. Tracy takes 3, that's the only answer that makes logical sense.