Start with the evidence
Retain both documents and label each amount by its source. Gather any available conversion and fee detail before explaining the difference.
Work through the example
The receipt shows EUR80 and the statement shows USD88. Those numbers suggest a relationship to investigate, but the ratio alone does not establish whether a fee was included or which rate policy applied.
Make the next step clear
Link the sources and leave unsupported explanations as questions. Do not rewrite the receipt as USD88 merely to match the statement; preserve what the supplier actually issued.
Keep the source context
All exchange rates in these worked examples are fictional arithmetic inputs, not current market rates. A business must use the source, date and method appropriate to its own review and approved accounting process. Keep original currency amounts available throughout.