Use $20,000 of your client's account in the two foreign currencies which you have selected to invest  in based on a margin of 2% which gives you a high leverage (50 to 1), meaning you can invest up to $1,000,000 or 50 times of your client's balance either in currency spot market or currency futures.  To keep things simple, use the currency spot market and you are recommended 

to choose  two hard currencies: British Pound and Japanese Yen.  

USD/JPY: $1 USD=114.76 Japanese Yen

GBP/USD: 1Pound=$1.36 USD

 

Calculate your return for each investment and overall return.