Recovering the original from a post-change value: "after a 20% discount a coat costs 48" means 0.80x = 48, so x = 60 — the 48 is 80% of the ORIGINAL, not of itself. To undo a multiplier you DIVIDE by it; the distractor 48 × 1.2 = 57.60 adds the percentage back and is the single most common percentage error, because the two bases are different numbers.