const rates: Record<string, number> = { USD: 1, EUR: 0.85, GBP: 0.73, CAD: 1.25, AUD: 1.35 }; export function convert(amount: number, from: string, to: string): number { if (from === to) return amount; const fromRate = rates[from] || 1; const toRate = rates[to] || 1; return (amount / fromRate) * toRate; }