Office A earns $52,000; office B earns €40,000. With £1 = $1.25 and £1 = €1.15, how much more (in £) does one earn than the other?

Convert both amounts into the same currency first, then compare. The correct answer is £6,817. Traps to avoid: £19,000 comes from the "multiplied not divided" error; £12,000 comes from the "compared without converting" error; £76,383 comes from the "added not difference" error; £13,217 comes from the "swapped rates" error.