well, we can simply find how much for each tulip in each store.
store left has them for £9.8 for 4, that means 9.8 / 4 = 2.45, so £2.45 for each tulip.
store right had them for £4.2 each, but they went down by 1/3, so hmm a whole is 3/3 so if we take away 1/3 from 3/3, 3/3 - 1/3 = 2/3, so the new discounted price is really 2/3 of £4.2, that's (2/3) * 4.2 = 2.8, so £2.8 each.
so store left has them cheaper, doesn't matter at a dozen or less or more.
how much is it at store left for 12? 12 * 2.45 = 29.4, or £29.4.